The amount of salary has only a significance when calculating how long you spend at home to be able to build an aircraft or do your own plumbing for that matter .... if you stay at home enough you have all the time in the world.
Usually find that lower to no salary group are either retired or home every night (with exception of IT people who seem to be able to make plenty and stay at home) this then will give them the TIME to do it. Thus if I was interested in building my own Jab/Tec etc (refer polar bears) I would have to give up a large portion of that income which then (fairly) would have to be added to the building cost.
This also explains why some manage to do relatively small hours flying time each year.
cheers