The main argument against piracy is that it means no money goes to the creator of the work, unless you actively go out of your way to give them the money. You go out of your way to give them money in purchasing the work when distributed normally.
There are resource-based arguments that render piracy a bad choice for the individual. Obscure media on torrents usually can't be fully torrented due to few seeders. Some don't even exist in a way that can be torrented. There is a time cost to pirating that is usually, but not always longer than downloading directly from a storefront. As far as physical resources, other than the cable which has to be laid by your ISP, and the storage space and computer which needs to be purchased or owned by the seeder and the leecher, and electricity to power their devices, there's little physical resources that are being used in pirating. It's not none, but it's close to none in the 21st century. It also comes at no resources taken from the creator. You don't take money from the creator, instead you don't give them money.
The convenience offered, can also be discussed. Torrenting programs are pretty poor for an end user, and can't really compare to a storefront which is designed to maximise sales. There is also shared suspicion of torrented files containing malware, but that only really holds for executable files. In the case of executable files, you can choose to either sandbox it, which requires technical expertise, or to purchase it from a storefront, which generally(but not always, malware can slip through the cracks) guarantees that it will be safe to run.
With the point of giving money mentioned, it is worthwhile adding that the equivalent legal platforms also frequently give creators the short end of the stick. Spotify gives music creators a sliver of money for the time they put in. GPL Licensed code, can be compiled and sold, but any technical person can come along and fork it, compile it and make it freely available(an example of this is Conversations and the Conv6ations fork which are XMPP chat programs). As a result, sometimes there is almost no de facto difference in pirating or acquiring it legally, to the creator, but a significant difference to the end user. De jure, there is a difference as it's illegal and a lot of money is put into piracy. This legal difference can also have a psychological effect of fear. Some people simply do not want to disobey the law, even in acts of civil disobedience out of fear for the consequences.
Another argument against piracy, is the number of jobs it "creates". DRM has to be produced, and battle-tested and continuously improve as it is an arms race against DRM crackers. There is also a whole area of copyright law that lawyers train in and can make money from. As a result, by pirating, you help in justifying these industries further, despite fighting against it as an individual. I put the word creates in quotations above because I do not believe these jobs provide value to society. Copyright law(and hence those lawyers) could provide value, especially if reverted to a much earlier variant and understanding of it(28 years, renewable once for another 14 years in America, 1831), but the modern variant(death of the author + 70) is utterly broken that products become mostly unusable for the public to expand upon for about a century or 2 centuries. It will only get worse as health technology improves, making the author live longer.
its not morally right at all but i do whatever
An argument based on morality, or comparison to theft can be put forward, but that depends on the individual subscribing to the same moral principles(which can be fair on a local level, for example in Ireland which is a strongly Catholic nation so by culture and tradition people share Catholic morality for the most part, hence it being pro-life on abortion). To put forward an argument of morality on the global level falls apart very badly as different systems work best for different people. The stereotype of the Russian or Chinese pirate holds because it's true :^) and American law applies to America not foreign nations(though allies can help them enforce it). The problem with theft as an argument is it requires resources to be stolen. The only other claim for theft is if a seeder is seeding unknowingly(usually due to insecure computers) so you are stealing their bandwidth, electricity and computation for piracy. Interestingly this isn't theft from the creator but theft from a seeder. Of course most people won't be culpable of that, nor care for it.
The solution to the main argument is a support of more crowdfunded projects. If there is no support for it, then unless the creator really wants to make it(art made for the sake of art), or needs credentials of finished works, or wants a following, the product is unlikely to be manufactured. For digital works I believe this is a pretty good solution as the monetary cost is almost always in manufacture and production, and rarely in distribution or maintenance(there are some cases where the latter needs constant funding like in MMO games or online services). This breaks down in the production of very low-demand goods, but the same ones would also suffer similarly badly under the typical storefront method. The other way this fails is that the majority of crowdfunded projects use middlemen, which suck up their cut. I quote the above, as media manufacture is distinct from media distribution.
My Argument against Piracy: If literally everyone pirated everything all the time, then eventually media would collapse under no funding and we would lose the ability to generate anything new. We cannot have a functioning entertainment industry without cashflow. Inb4 >bUt mUh fAvOrItE iNdIe aRtIsT sElLs hIs sTuFf fOr fReE. That is not a reasonable standard for anything long-term. Even if quality stays very high, that will only exponentially increase the duration that it takes to create media of high quality.
I quote the above, as I think it confuses manufacture and distribution. If everyone pirated, then the status quo of paying for completed works would collapse, but then the payment would move towards manufacture as opposed to a finished product. Also where do you get the idea that just because a person sells something for free, the duration of production increases exponentially? Video producers sell videos for free(YouTube, Oddysee, Peertube e.t.c.). They make their money from people funding their manufacture(patreon or liberapay) which is how they can justify removing advertisements too. I don't pretend that this is an optimal solution, because a lot of these crowdfunded works are scams, or simply unfinished works. Due diligence is required of the consumer.
I will personally continue to support piracy, and fund the creators I like, and purchase well within my means.