The problem with revolutions is that people who have the ability and knowledge to participate in government rarely find it necessary to rebel- either they're part of the ruling class, and thus more likely to be rebelled against, or the system has enough citizen participation that revolution is not needed to solve the problem in the first place. So the people rise up, take power, and then realize that they have no idea whatsoever what to do with the reins they've just seized.
Besides that, once the war is won, the leaders of the revolution start to realize that they are now the top dogs in the kennel. Now that there's nobody strong enough to tell them "no", they can start getting back at old rivals, undercut new rivals, or even indulge in vices that were heretofore forbidden to them.
This usually results in an extremely incompetent new government, and one that lacks the internal cohesion to survive long enough to figure out what the hell they're doing. Even when you're dealing with somebody like Simón Bolívar that has the prestige to hold things together, that person's influence rarely outlives them, and is thus not enough to offset the issue.
The primary exception to this is colonies that were already mostly self-governing, and thus were simply promoting the colonial government to a national one. The most famous example of this is the American Revolution, but most other British colonies were able to transition well to independence for the same reason.