I don't change the amount I bet when I play slots because I still enjoy it. Those who gradually increase their amount of bet might be those who can afford it, but I can't. But I could say that even if I bet the same amount at each roll, I have won many high multipliers in 5 digits and it was so damn satisfying when I received it. It's because I didn't need to force my way into doing a "martingale-like" bet. What I bet is enough for me, and I don't want to risk too much that I cannot afford anymore.

I think it all depends on each gambler's purpose. If he is really there to win as quickly as he wants to, then he might do the same trick as you said.