Does generative AI harm CG stock industry? Of course it does, you'd have to be very naive to think otherwise. Having said that my sales on cgtrader this month are significantly better than they were in disappointing summer months. If not for reduced royalties it would be a second best month of this year. On the other hand, situation on all the other marketplaces is catastrophically bad, especially on fab which is as good as dead for me - 3 weeks without a single sale.
To be honest i try not to worry about sales too much anymore. You just need to accept the fact that reliable income from selling stock models is becoming a thing of the past and start looking for other ways how top up your budget.