Not sure if they're serious, but certainly a LOT of people in my experience think of cryptocurrencies as a company, so they presume by "buying in" the company (and by extension devs) make a profit, and it's not hard to see people believing the same for mining fees. There's a very prevalent attitude of "I bought in, what are the devs doing to make me a profit" and of course the answer is that in a fairly distributed coin, coin devs typically hold a tiny fraction of all coins, and value movement is of very limited relevance to them.

Edit: Yes yes, Satoshi, blah blah... no. Satoshi essentially solo-mined Bitcoin for the first several weeks of its existence, because no-one else was that interested. Any new coin release can expect thousands of miners competing for the block rewards, not one person grabbing all of them for weeks.