So from your example, if you raise $30k for mining equipment that generates $600 a day everyone would expect to get a return on their investment in 52 days. This of course is assuming the difficulty and probability of the coin mined don't change. What happens when it starts generating less after difficulty increases etc? If you add more mining hardware wouldn't that mean that the initial investors return will slowly shrink overtime unless they keep buying more tokens?

Just trying to wrap my head around this, seems like a good idea in theory.