Bonuses are great if they are very transparently tied to external events (exceeding revenue goals etc) and not any internal politics. Worked at one company where one could take the annual report and apply the published formula to come up with your bonus. That was great.

Making it unpredictable and secret is super toxic though. At one SV hardware company we had a great fiscal year, exceed everything and then they announced that based on their super-secret bonus formula, it came out to 0.05% of target. They actually paid out that 0.05% which felt more insulting than just calling it no bonus this year. I did quit the place after that incident.

A much better way to handle it was at another SV hardware company I was later. Same scenario, best fiscal year ever, etc. But bonus computation based on secret formula came to zero. This company had actual decent humans in charge (based on many events not just this one) so they acknowledged that the formula needed fixes and retroactively changed it to account for the exceeded financial targets. Sadly they still kept it secret but in subsequent quarters it did seem to track financial goals pretty well.