Currently joining a startup has become this sexy thing that everyone wants to join to change the world. Now, I agree this messaging is correct and should be the goal.
What people miss out on in terms of startups that succeed and "make-it" doesn't come from just a great idea or luck. It comes from a combination of three things.
1) IDEA: something that provides insight into a service/product/sector that is in need of innovation. Messaging clients are old school, let's build Slack a better one.
2) TIMING: The ability to deliver on this idea/innovation at the right time. Launching palm pilot was close but too early.
3) EFFORT: This is what separates the amateurs vs the pros. Startups that win put in 10x the effort and execution into something for 5-10 years before they win. Most startups don't get there.
There is no magical formula to becoming a successful startup. It's the same as a successful musician, athlete, normal business; it involves hard work over a period of time.
The main difference, so smartly said by Paul Graham, is that startups do it in a compacted amount of time. Instead of taking a lifetime to become great a basketball, startups go crazy for 3-5 years to become great at what they do.
So if you want to change the world, and maybe make it rich. Make sure you're mentally ready to dig at it for a minimum of 3 years and if you can survive and grow for 10 years, you might just make that IPO a reality.