It's luck because you have no direct control over it - it happens by unpredictable circumstances.
Think of networking, and imagine every person you meet and build a rapport with as non-parametric distribution that you're randomly sampling from over time (future interactions). You have no clue if each sample is going to yield positive results, but you can increase your chance of a positive outcome overall by increasing the number of distributions (people) you're sampling from (maintaining relationships).
So much of it ends up by random chance, what else could it be but luck?
Think of networking, and imagine every person you meet and build a rapport with as non-parametric distribution that you're randomly sampling from over time (future interactions). You have no clue if each sample is going to yield positive results, but you can increase your chance of a positive outcome overall by increasing the number of distributions (people) you're sampling from (maintaining relationships).
So much of it ends up by random chance, what else could it be but luck?