I am a $15 regular in chico and tried moving to $30 after doubled my bankroll with $15.
But unlike $15, there is literally NO fish in $30, and i face only regs and regs there. IDK how they profit with 30s?
it seems impossible to win at all, i doubt if even a gto bot who plays perfectlly would win anything.
But they are sitting there. everyday. why are they doing this?

I think a lot of this is the classic adage "if you can't spot the fish, you are the fish." More applicable to HUSNG in the way of "if you can't find the weaknesses in these opponents, then you have some work to do still."

Players play higher stakes on tougher sites than Chico and do very well still, so I think you're just not recognizing the weaknesses in these opponents. Even the best $30s players have plenty of weaknesses/leaks that can be exploited.

Granted, it's possible you're not recognized and the better regs on this site are just sitting you over and over. That would make the $30s feel a bit tougher to you initially. Variance can also be a big challenge, as can mental hurdles in moving up. It sounds like you've potentially been playing for a short period of time as well.

I think it's not about variance, because I got averagely +1% roi after rake against these regs over 1000 games. That's not an unlucky data, but still unacceptable compared to playing $15s simply.
Maybe i should study and continue playing when i can really win them instead of breakeven... Thanks for advice

1% ROI over regs is pretty nice. I'd look to build upon that and start picking out the weaker ones to play more frequently and see if the better ones will avoid you. Assuming these regs prevent you from playing weaker opponents, you just need to prove yourself for a little longer and they'll likely stop sitting you if you keep this success up.

I see Bet on regs avoiding me, this is a good idea! I never thought about that