That's a reason, for sure. But I would say that I have become very cynical about this type of reasoning for the following reasons:
1) If you are interested in working on interesting technology, and the idea is that a traditional corporation provides only soul crushing but possibly more stable/well paying work, then I would simply say its better to have a side project instead of working at a startup, because they are unstable.
2) If you are interested in doing work that will change the world, be aware that if you aren't the boss of the startup, then you can be gone in a second because of profit reasons. Better to start your own non profit like Watsi
If the chance of making millions was 1/100, maybe I would try it. But it seems the real chance is 1/1000? Possibly even 1/5000?