Most startups funded by YC are from first time founders, and definitely not by people post-exit. The whole idea, and value that the startup ecosystem brings is giving opportunities to anyone to enter the field and compete with the establishment.

For me, personally - before the startup ecosystem happened in my country, it was extremely difficult to break through. If you worked for a large entity - good for you. If you wanted to do something on your own - you weren't treated seriously, and it was very difficult to get through.

Now, people from anywhere, can visit meetups and hackathons to get up to speed, and gain connections. And accelerators like YC provide resources and mentoring to the ones that are the best.

Also, notice that YC has an open application, and they don't look at your social status, your wealth, nor your connections, when judging your application.

Of course it's not perfect - being from US, or the bay area, helps. Knowing people who got through YC and can help you prepare your application also helps.

But I haven't heard of anyone with a better idea for solving this.