Remember the last time you got an item for free. You probably didn't worry too much about it, because it didn't cost you anything. You didn't treat it that carefully.
Compare that to something you bought for yourself, that you had to work hard for. You probably took a lot of care for it. You probably really paid attention to ensure it didn't break.
I feel like this is the mentality difference. Something free = no value = we can treat it badly. Something not free = it has value = we are more careful with it.
The nicest customers I have for my Saas product are also the ones who have the largest accounts. The ones that pay $15 a month for a single user on the cheapest account are always the ones asking for a list of like 50 new features to be implemented yesterday or "the product just isn't gonna work for us". Yea ok, because your $15 buys you a right to own my entire roadmap... not.