The big bummer about acquisitions is that they can change the terms of the deal however they want, including devaluing or even outright cancelling all the common stock. IPOs seem much safer in that regard, but obviously a rank-and-file employee has no say in which direction the company goes.
To be fair, though, the bad deals the employees see at acquisition aren't necessarily always due to sketchy exploitation bullshit. Sometimes a bad deal for employees is the only one the board can make, with the alternative being bankruptcy and everyone losing their jobs. It does sting that institutional investors and founders will sometimes get a decent return on their investment/time in those cases, while employees get table scraps, though.
To be fair, though, the bad deals the employees see at acquisition aren't necessarily always due to sketchy exploitation bullshit. Sometimes a bad deal for employees is the only one the board can make, with the alternative being bankruptcy and everyone losing their jobs. It does sting that institutional investors and founders will sometimes get a decent return on their investment/time in those cases, while employees get table scraps, though.