Look at it this way. There are plenty of talented engineers, designers, and entrepreneurs out there trying to build the next big thing. Due to the incredible scale and reach of the internet economy, those who succeed will become fabulously wealthy. But most will fail (or at least not reach that scale) due to various circumstances---a misstep in execution, a superior competitor, our simply bad luck. There are certainly many small successes, but success or failure can seem like an incredibly binary event.
Why should engineers shoulder that risk? That’s the raison d’etre of finance and investment. Let those with capital take on the risk, and give the engineers enough security so that a “failure” doesn’t put a talented person out of the game. If every startup that demonstrates that it execute on an idea and can clear some threshold of viability gets a reasonable exit, then the investors will still get enough Facebooks to generate a good return, and the startup teams are much less captive to chance and fortune with respect to whether they can pay the bills or not.