My opinion about buying bonus rounds is that it takes a lot to win because it is a tactic of the slot game that lets people buy bonus rounds instead of waiting to get one and the odds of winning a lot if it is from the bought bonus round is not that high like you won't likely to get investment back. its like buying bonus rounds is part of the game's design to maximize profits, not necessarily to increase the player's chances of winning big.
I've seen one streamer, he made a buy bonus of $150,000, that huge amount of money, I can't remember which game it is, probably it's "Wanted Dead or a Wild" game, and you know that's the turn around, just freaking $9,000 for that buy bonus.
Yeah, tried a couple but for me, not the worth as it is. And it's going to be a trap for us gamblers, yeah, it's the fastest way to win bonus rounds, but still a big risk as it might not give you something in the end.