I've never played Animal Crossing so I have no idea what a bell is or what it's worth, but a million bells sounds like a lot! How do they get a million bells?
If you have the tool to play homebrew DS games, you can use some tool to copy the AC DS save file and then edit it.
But if you're not a cheater, you can earn money easily on AC after some preparation.
Money making tips:
1. Fishing is a great to earn money, you can net at least 100000 bells per day and more if you spend more hours/day. Not the right choice for players that can't play more than one hour per day.
2. Foreign fruit orchard. Best for those that don't have much play time/day.
Foreign fruit sell for 500 bells each and one tree grow 3 fruits/3 days. So you can make on average 500 bells per day on each tree that you plan.
One town can have about 12-14 trees per 16x16 squares(if you want to keep your town in perfect condition if you don't care about that you can fill up with more than 14 trees per 16x16). And your town have 16 of that 16x16 square.
So you can have about 192-224 trees if you keep it your town in perfect condition or more than that if you don't care. That is on average 96000-112000 bells per day.
Need preparation to do it, but I managed to fill my town start with one single apple that I got as a gift. If you are like me only have one foreign fruit(if you don't have friends to wifi with), then you better maximize your chance of successful growing the tree by cutting down and existing tree then plan that foreign fruit in the same spot as the tree you cut down.
At first I plant all apples that I got and don't sell them. Now I have about 200 apple trees while still keeping about 10 orange trees(native of my town) and less than 10 non fruit trees(you get bees/money(100 bells)/furniture randomly if you shake these non fruit trees).
3. Talk with the animals and be friend with them. Sometime they give you gift and you can sell them. Or you can write to each of the animals each day and give them gift(anything cheap), they sometime give you something back. But these are not a good money making trick, so I only do them for fun.
4. Digging up fossils and sell them, you get 5 new digging spots per day so you can get 1-5 fossils each day depend on your luck.
5. Selling shells. Not much money, but easy to do just walk pass your coastline and pick up any shells you find then go sell them. You can do this several times per day and each pass only take less than 10 minutes.