Work hard, don't be a jerk and you'll be fine.
This doesn’t always work. I have seen plenty of assholes easily climb the ladder, make tons of money while good people are stuck.
Example: A guy was making 60k, his employer spent tens of thousands on tuition so he could get MBA from a world class school. He took a new job a month after getting his MBA, doubling his salary. That is just one example, I have seen more. One of my CTOs mistreated nearly everyone, still kept failing forward. I’ve seen sexist and racist people at top positions. And so on.
This is not to say that one shouldn’t be nice, but to set the expectation that being nice automatically brings rewards. It does not work that way always.