Agree and disagree. Monetization is on one axis, passion is on another.
I think if you start off just making something for yourself, it may be hard to monetize it, because it's only optimized for how you do things. On the other hand, if you do something only for monetization, it's super easy to get demoralized and just stop. Furthermore, monetization isn't an easy to thing to optimize for - it's very hard to see where the sweetspot is.
But if you can find a right balance between creating something that you find a lot of interest in, and that a lot of other people would value, you can find a great balance of personal satisfaction and something sustainable.
I just find that whenever I optimize for money; I start making weird decisions; decisions meant to please others, who may not share the passion. I'm all for people paying me to create and share the stuff that I already am; but then it needs to come without conditions, otherwise we're back to square one.
I think if you start off just making something for yourself, it may be hard to monetize it, because it's only optimized for how you do things. On the other hand, if you do something only for monetization, it's super easy to get demoralized and just stop. Furthermore, monetization isn't an easy to thing to optimize for - it's very hard to see where the sweetspot is.
But if you can find a right balance between creating something that you find a lot of interest in, and that a lot of other people would value, you can find a great balance of personal satisfaction and something sustainable.