I don't think most people have a code for decentralized social network laying around somewhere. Its not a simple application at all, and it requires a lot of development. Such apps do exists today, but are not used as much due to practicality. I really do hope that you have though of some technical breakthrough that will make them more accessible to general population.
whatever, but it certainly requires a good knowledge of the code itself and a clear understanding of what it is for. Social network application requires a lot of daily maintenance work, updates, monitoring new trends and implementation etc... it is not a job for one man, but for the team.
But if someone
in this case OP had enough skills to maintain such a code, probably they don't need to buy it from someone, he will develop it himself.