Most of the questions have factual answers TPM provided. How long someone sticks with the minors and making it depends on the person.
A friend’s younger brother decided he didn’t want to sign despite being an 8th round pick offered slot money. He decided to graduate and go into dad’s business before taking over. He saw it as an easier avenue to happiness than busting it hoping to make it through the minors to MLB. My friend was a doctor in residency. She wasn’t interested in dad’s business.
Another friend’s son played minor league ball until he was thirty-four. He was waiting for an organization to ask him to become a coach. He’s now been a minor league coach for four years. Income isn’t an issue. Dad is wealthy. He will inherit half with a brother.
Covid may have put a wrinkle in the following philosophy. It used to be if in AA at 26 you better move up quickly or you’re done. Most of the players I’ve known gave up if still in the minors after 26-28. The pitchers were more likely to be the ones hanging on through 28.