It can be upsetting to have your creations taken. When I was doing oil on canvas painting, I hated to part with a single one - forget money, sometimes they're like your babies... Still makes me cringe to remember a floral I loved so much get mounted in a frame that ruined the whole thing.
Then, in the 90s, I started designing web sites. It took a few years not to get indignant and want to complain when I saw my graphics or even whole designs copied.
The web really did change things though, and after a few years of enjoying freeware, shareware, (look at calibre, for instance), and all the free sites (like this one!), ebooks (like Harry's contributions) ....it got easier to go with the flow.
Still can irk at times, and leaches are ugly, but it usually balances out, and life's just too short to sweat the relatively small stuff.