So true. I'd expand on that with a more specific example: game modders. When i look at all the energy spent on game mods which bring significant (gratis) value to commercial games, i can't help but wonder what the FOSS gamedev ecosystem would look like if all those dedicated people put their energy on free-software ecosystem.
Minecraft for example made a fortune on promises of later open-sourcing the game and deriving value from all the volunteers building mods.