Does it make sense to publish papers/ theses online?
My goal is to earn a bit with the texts


My understanding of book publishing is that making money is really hard, and even harder if you do not have the backing of an established publisher. Established publishers often have contracts with university libraries that guarantee them a minimum number of sales. They generally like authors who will then teach off the book which gives them some more sales. When the author convinces colleagues at other schools to teach with the book also, profits can be made. You do not seem to have that type of network, so I doubt you will make any money.

The hit rate of established publishers to actually turn a profit is pretty low. With their network and approach, their costs are generally covered such that a couple of successful books is all they need. This means they scoop up anything that even remotely has a chance of being profitable.