I've done most of my renovations personally. Rebuilt the entire downstairs bedroom (walls, floor, window), laid drywall, painted, laid floating floor, moved sinks etc etc.. If you've got the time and the skillz, it's often worth doing yourself. If you look at something and say "Should be easy" - you're usually wrong. And sometimes, the work is more extensive than you could possibly have imagined it.
Renovated a bathroom downstairs... should've been easy. Tear down the old cabinet, replace tile, paint, new cabinet, new sink, light fixture..presto!
Got most of the way done and then had to stop when the floor started giving way.
Remove floor's plywood..oops, rotting wood, rotting supports. Took a step back and called a plumber I know. The entire piping had to be changed. Breaking up concrete, laying new pipe, swapping the sink and toilet's locations, putting in a vent, new concrete, new supports, new plywood. I took over after that. Bathroom looks great now.
Took a pro to see the layout as it was v. how it should've been built.
It's the discovered parts of the job that cause headaches.