First of all, it should be noted that by "truly profitable investment" I mean something that's of profit even "spiritually". Not just cash.

It's possible to invest in bad art, even immoral art and make a profit. Would you do it?

Such a decission would have to be based on a hierarchy of values, not just an opinion on what good art is.

Because it doesn't at a first glance look like a "spiritually" profitable venture esthetically speaking, in order for me to do it, it would have to somehow be a good deal in the long term. If the true (spiritual and material) short term cost of holding the art was small and the monetary profit large, it could for example be that in my particular case holding bad art in order to sell it at a profit, would enable me spiritually in the future.

I would not. Because I don't want to live in a world like that.

For example, would you invest time and/or money in Steemit?
Take some time to consider the fact that the platform hosts and even pays out money as rewards for the expressions of many different tastes and ideologies, a large portion of which are very clearly opposed to Objectivism. Yet here we both are. Why? For me, because the combined long term profit of supporting the system is so much larger than the short term cost of enabling some behaviours which I dislike.

Just like I don't want to live in a world where peoples self esteem and productiveness is undermined by free stuff.

In actuallity, nothing is or ever will be "at a zero cost". It would be an imposibility because the world runs on productive effort. But I agree, I would not want to live in a world with far less productivity and I would not support the implementation of a version of the UBI that would risk that.