I'm new to cryptocurrency and dont find answers to some question yet.

i tend to compare with stock exchange and get the answers and however failed miserably to get the answers in this way.

what is a mining and how is it fair with those investors who pay 100s or 1000s of dollars to get the coins. where as a techy who have invested some thousand and keep mining different coins and fetch coins.

what is the concept behind mining technology and how is it useful in generating revenue to particular instead of continuing ico as some coins do and some coins dont let mining at all.

i'm cracking head to understand and don't get any answer.