Unfortunately Bernie can't raise enough money to be taken seriously by those who have the power to select a candidate...
It's the voters who select their candidates, or allow them to be selected by someone else. It's all very simple.
And when was the last time that there was a president who wasn't from one of the two parties we have today? When was the last time that either house of congress had a significant number of members who were not from either of the two parties?
And the game is rigged within the two parties, as well. We have seen before that most of the candidates - specifically any that vary from the party platform - are systematically eliminated from contention well before most voters have a chance to make their interests known in the primaries and caucuses.
We've also already seen that Bernie has committed to only running as a Democrat. Once he is eliminated - which will probably happen at most two weeks after Iowa - we won't see him again as a presidential candidate.
So no, the voters do not select their candidates. At least, not for president. We've seen that some people are interested in re-separating the voters from the senators as well, which is a related matter.