I'd like to respond to your general questions with some personal opinions as well. I don't know if they will convince you to invest in cryptocurrency longterm, but I hope it will give you a new perspective on it.

Q1. Why will people use it?
Why would people use it as opposed to physical currency like the US Dollar? Cryptocurrency is surprisingly liquid and can be converted quite easily with cheaper conversion fees as opposed to say...going to a bank with $100 and wanting to change that into Euros. Micro-transactions also become possible so the values of your goods and services are calculated more accurately.

Q2. What is the monetary benefit for coin holders when people use it? (other than price change)
Some coins / cryptocurrency are used to be able to use a company's technology. For example, the tokens we are minting here at Kr8os / Kr8os Project are so that those who have purchased our tokens can have access to our adfraud blockchain solution. Those who would like to use our solution but do not own any of our tokens unfortunately cannot access our technology.