what your friends have done is not what can happen to you. There is no such thing as taking a back seat, its already been said, and never ever employ relatives, because if you fall out, it will be ten times worse. There was a programme on a while ago that showed a couple who bought a pub, then all the problems started to kick in, unreliable staff, food orders that didn't show, having to work your backside off, and the list goes on. They invested a small fortune, and lost the lot.
You are young, and as many have suggested try working behind a bar for a bit, even part time if you can, because it would give you a taster of what you would be letting yourself in for. But working in a pub and running it full time are two different things.
Pubs fail for endless reasons, high prices, location, even where the place was the hub of the community, types of food or not on offer, and you end up having to do so much to pull in the punters, much more than in the day, when it was the choice of many men to go to pub for pint after work, meet up with friends, and at weekends.
Many pubs have been turned into restaurants, gastropubs, or shut. London pubs have been closing at a rate of knots, many decent, but the demand isn't there anymore. The smoking ban has put a nail in the coffin, add to that the greedy chains who own many many of these pubs. I would put any money into a home, because the other factors is that people who own pubs, usually live on the premises, and when they go bust, they have no where to live. Hard work for truly not a great reward.