In my opinion, it depends on the individual. When people are playing, they need to monitor how quickly their bankroll is depleting and, based on that, devise some way to reduce the rate at which it depletes. This also depends on how people play; they need to decide when is the right time to increase their bet.
They can't act on emotion. For example, they placed $2 on a multi-bet and won $20. Then, on the next bet, instead of continuing to place $2, they decide to increase to $6 on each bet, resulting in a losing streak and losing their entire bankroll. This type of mistake is very common, as I've seen.
Yes, it all depends on the individual, but increasing the bet is certainly done by players when their bets have yielded results, especially for players whose goal in gambling is to seek profit. I don't think they hesitate to increase their bets. Those like this tend to be more daring in betting, even though they may not be ready to lose, but the courage to increase their bets is real.
Perhaps you've not only seen it but also experienced it yourself. What you describe is behavior that I believe everyone who gambles has done, so it's certainly a certainty that increasing the bet is something they do.