1) Content needs to get paid for, if you're watching an illegally restreamed match then you're not rewarding people like me for the hard work we've done to get that game to you. It's not just faceless corporations, we're people and it's really hard to make a profit in the streaming world, so every viewer counts.
2) We don't decide how much the rights cost and on top of that we spend millions getting it to our subscribers (e.g. cloud providers, CDNs, developers). We've got to pay our bills, again, no streaming service is scalping right now. Delivering Tbps of streams is hard!
3) Many live sports re-streaming services really are run by organised crime gangs. I have involvement in some revenue protection work, there's not just hacking, there's also money laundering, we've even encountered links to people trafficking in the same organisations. I'm sure you think it's an exaggeration, but it's real and it's not just some guy in his basement doing this stuff.
4) The companies that invest in technology for this stuff often invest in things like AV1, FFMPEG, Exoplayer, stuff that's available to the wider open-source community. We, as organisations, contribute back to the world in other less obvious ways. Hurting us hurts the community as well.
5) Lastly, I presume that most people here get paid for their work, or at least would like to be paid for what they do in the future. Put yourself in my shoes: how would you feel to have your work ripped off? Oh, and then someone else profits from it? Hmm, not cool. That app you work on? That website you support? Maybe you hate your employer enough that you don't care if they get ripped off, but most of the people I work with love their work, so consider that as well.
I am sure people will argue against all my points, but they stand none the less.
What I will say, unofficially, I sympathise with people who cannot watch our content because it's not available in their market and I also have some sympathy for those who are too poor to pay. But I'd assert that 99% of the people who pirate our content are not too poor and have ways of watching legally, they just choose to go to the dark side.