I do it for the following reasons in order of importance (not that I know any of them actually work but it is my rationale for doing it):
1. Hiding increased bet sizes based on my hand strength against fish. Almost all of my non river, non inducing bets are 55-95% of the pot. If I think someone isn't really paying attention, I'll bet larger for value and smaller when I have air. If I think someone has picked up on this, I'll balance my range more and occasionally play the leveling game.
2. It diverts attention. If someone has to determine rough pot odds
, it's harder with weird numbers. I can do math quickly in my head so I think this creates a non negligible edge in the decision making process.
3. The visual chip effect. Larger amounts of chips looks more intimidating. Whether this actually has an effect on other people's decision making, I have no idea.