As a stake holder burn posts benefit you, it reduces the amount of coins in circulation.
And many witnesses have some really heavy duty hardware that costs cost to what they earn as a witness.. Many need backup servers in case their primary misses a block. And those setups are not cheap.
I believe in the halving effect long term on crypto will be all the marketing Hive needs. As BTC rises from the reward halvings over years so do alts.. they always have and will probably continue to do the same.
Hive is in a prime place to take on more users, and seeing the price of Hive rise by many times due to normal altcoin trends is all the advertising it needs.