Wanting to do something to earn loads of money is definitely not the way to go about it - it just sets you up for failure. Richard Branson, for an example, said when he was setting up some store or something he wasn't thinking "Oh, I'm going to open this shop, and I'll try and make as much profit as possible, then I'll open more", he was thinking "I'm going to make this a really great shop" and then the customers came.
Do something you like and do it well, be a bit entrepreneurial or whatever, and you should do pretty well.
From personal experience, I can say a) that if you do something you hate, making lots of money from it does not make it any more fun. & b) Money and material possessions really do not make you any happier - you buy one thing then immediately think of the next thing you'll get. Money makes you more comfortable in misery, but of itself it won't make you happy. You need a fulfilling life, and love, great friendships to be happy, and likewise if you have all those things then money doesn't matter.
You should just see some of the Secret Millionaire, where some of the millionaires moan about how lonely & unfulfilling their lives are - they are the same as any other person.
I think if you chase money then where does it stop? There are always ways of acquiring money so are you ever going to have enough? You can only have one wife, or so many kids, but money is infinite - it'll be like a donkey chasing a carrot, you'd keep going forever and never be satisfied. Of course, everyone wants enough money to be comfortable, but if to 'be really rich' is your one life goal, you are never going to be happy.
I know it's a Bible quote (1 Tim 6:10), but the phrase "The love of money is the root of all evil" is still very apt IMO.