the reason of why so many games flopped is...

[Zlejedi]

I'd say there are two reasons:

money - average game is too expensive for the value it offers (mirrors edge for example) and as such it's too expensive to be bought by those with a lot of free time for gaming (as those groups who have a lot of time usually have smaller income)

time - typical young adult can spend only so much time on gaming each week and it can take weeks before they finish a game which leads us to the point that they need only a few games per month.