Is buying ICO always return the same amount of altcoin the investor invested?

[sotoshihero]

i think ICO is like gambling, you may win a lot or lose a lot. it might be easier to choose the right people, not the project.

Yes it can really be compared as gambling but if you did chose the right coin then you might win or gain profits and this is the hardest part on choosing a coin and does have a good potential.Its not an easy thing to carelessly chose and for op it depends on devs if they would pay up equivalent on thr amount you invested but mostly this do happen.

True. It is like a gambling also and it depends on owner/developer how honest are they. Not all ICO's returns are the same. Some are terminated when the target is not met and disappear without any trace.Investor are left behind wondering.

[noictib]

Does purchasing ICO very rewarding? Yes I know there are lots of ICO scams, but lets talk about the genuine ones.  
For example if bought 100usd worth of ICO, will the value of ICO I bough remains 100usd or higher?
What if the altcoin ICO doesnt meet the target purchase amount they are expecting for. Will I get the same amount of ICO worth the money I invested?

Most probably I will say your Investment will remain constant Because I know that most of the ICOs are scam but few of them are really profitable ICOs .
So here most of the times in the Investment of the ICO you will not get much profit .
But here I will suggest you instead to invest in the ICO , buy the altcoin at the instant after the launch Because after the launch in one week the altcoins price will increase , in this way you can make some better Profit without altcoin ICOs Investment .
So here change ICOs into Trading .