So lets say I put in $100 dollars. I buy while its at a low of $10,400. The price goes up to $10,400 and I sell. Whata my profit?
You gained no profit because you sold it the same amount when you purchased it. You will gain profit if sold it with higher price. Total amount when you sold it less the amount when you purchased it and the fee equals profit(if possitive) (if negative then it will be net loss)
It's easy you're buying bitcoin at price 10,000 and later the price of bitcoin increase up to 10,100 then you're in profit and its vice-versa is losing.