if i launch my own coin how i will get profit ?
It depends on how good the coins that you are making. There are certain type of investor that look for a specific road map for the coin before they invest. You will get profit if your coin manage to get into the market because coin developers 1/4 or more of the coins that is out in the market.
how i will manage development and other expenses ?
You will be needing a lot of people to do PR for your coin and team of other developers and staff because you cant handle this job alone. So for expenses you will be needing a lot of money.
for example Sathoshi made bitcoins but i am unable to figure out does stoshi getting reward from it or maybe earning ?
There are various rumor saying that Satoshi owns half of the bitcoins that is out in the market i dont know if its true but if really own them then your question has been answered.