Hi I run a masternode and features depends on which crypto you choose.
Yes it is an investment but it is being part of the network and helping it to grow.
Masternodes helps anonymity but they also give owner the right to vote for coin decisions and spending balance.
Plus they help price stability because stored coins can not be spent.
There are masternodes with unrealistic ROI but they are exceptions.
Plus ROI decrease each time a new masternode is added.
Bye!