A little of both.
I run a full time business (non pinball related) that eats up a lot of my time. Between that and family, I simply don’t have enough time to allocate to repair and restoration all by myself.

Besides pinball I also collect arcade games and EM games and that part of my collection is much larger than the pins and requires a ton of maintenance as well. Add it all up and I own close to 100 machines in total which is more than I can take care of by myself.

In a lot of ways it boils down to how much value I think my time is worth. I love working on games, but on an hourly basis this is a money loosing proposition for me. I can make much more money if I focus on my business than if I goof around in the garage working on games.
Hence I will outsource restoration and major repair work.
Once a machine is dialed in keeping up with the basic maintenance is normally pretty easy.