Any time spent creating a cosplay is time not spent doing paid paintings, just like the freelance copywriting that Ginny DiGuiseppi (Ginny Di to her fanatics) does that allows you to pay lease.

This valuation on time that’s spent on unpaid paintings versus paid work is referred to as opportunity cost. Mike Futter, creator of the GameDev Business Handbook, defines opportunity price as “alternatives forgone whilst you make a choice in allocating resources.”

https://www.ccosplay.com/