No. No, no, no. If I make $40/hour, and it'd take me 3 hours to build my own presets that cost $20..., well the math is pretty simple.
Hmmm, let's see... Work one hour, buy the presets, save $20, and have 2 extra hours to play instead of tweak.
Now if you prefer to spend your time tweaking, that's a different thing. But your example doesn't shake out like you said for everyone.
If it's not something you want to do yourself, you pay others to do the things they can do cheaper than the work-value of your own time.