We sold our house and bought a boat last year. Have been living on it since then whilst getting it together and sorting out our cruising budget.
I'm 32 - husband is 38 (so not under 30, but we think we are young). We are not in an ideal position of having loads of cash behind us, but think life is for living and so will set sail in May. We are based in the UK so plan to cruise down to the med for a couple of years before heading across the pond. If we can't make ends meet we may have to leave the boat for a few months each year and return to the UK for work etc but have enough for the 1st 18months. Truthfully I think that most people are generally too sensible to set off until they have their lives sorted - kids grown up, house paid for etc, hence it is possibly slightly easier to do when you are older. Good on them, thats what makes the world go round.
We plan to cruise for a while and then when/if we have had enough, set ourselves up for our dotage by starting a business or something - we should still be young enough.
20 years from now you will only regret the things you haven't done