Just because many successful companies are built on ideas that at first seemed ridiculous doesn't mean that ideas that seem ridiculous will be smash hits. Actually, most ideas that seem ridiculous are ridiculous.
If, however, a new market, technology or cultural bend turns up, an idea that exploits it might seem ridiculous because it breaks with social norm or accepted technological limitations but actually be viable. When Tesla started building electric cars they were ridiculed because few people understood that both the technology and the social acceptance was now at a point that made it possible. Had they started ten years prior the idea would probably have been ridiculous.
The trick is to be able to see the difference between the snakeoil salesmen, mad hatters and crazy inventors and the true visionaries. What makes this really difficult is that noone, including the founders, knows whether they're one or the other. There's a lot of luck and timing involved.
I'd also wager that the reason that mindblowingly successful companies often start out as seemingly ridiculous ideas is that if they don't have any competition in a niche that they can exploit. Microsoft, for example, were the first to sell software. IBM laughed them out of the room because software was just something that came with the hardware. The idea that you could sell software seemed as crazy as selling sand in Sahara. But because of a technological and cultural shift it was a good idea, and because it seemed ridiculous to "real" companies they had the market to themselves for the first vital years. Had they not been so lucky (or smart) with their timing noone would know who Bill Gates is.
I think you might be able to conclude the following:
"If you want merely to be well-off start a company that isn't based on a ridiculous idea. If you want a small chance of changing the world start a company based on a ridiculous idea"