Guess this very much depends on which position the financial investors have put the (technical) founders into. If they have taken a huge part of the equity for

Guess this very much depends on which position the financial investors have put the (technical) founders into. If they have taken a huge part of the equity for themselves and left the founders with far less than 50% such behavior might become understandable (many founders then might feel that it's not their company anymore). But if the founders still hold around 60% after financing rounds of >$50million and then leave a large part of their investors "standing in the rain" i.e. they just get parts of their money back this becomes dubious. Nevertheless such cases are very rare and most of the time some investors will still complain even if they are making a very serious profit but less they have been dreaming of. Best seen recently with Instagram when one early investor was labeled as not very clever even though they were making a few hundred time their investment (a few 10'000 pct profit). Generally if investors are unhappy, that those who have generated such massive profits for them benefit as well after they themselves have already been rewarded, something else is substantially wrong.