There are plenty of young software engineers who hear about first-year salaries at Google and expect similar comp packages from startups. (Are they being too greedy? Meh, they're just misinformed or need to take some time to recalibrate their expectations.)
There are also plenty of companies guilty of the same thing. Their expectations are too high as they turn away great candidates because they don't have a CS degree from a top school or have an impressive track record of open source contributions.
The OP listed "don't be greedy," which sounds familiar to me. It's easy to have a few bad experiences and then draw a blanket conclusion that every tech company is trying to squeeze me. My point is only that it's frustrating on both sides, and whether you're an applicant or a hiring manager, understanding what the process feels like to the other party will make the process that much easier for you.