Because it's as about as easy as it can get in the realm of gardening. I'm not going to detail general gardening techniques, planting seasons and all of the other earthy junk that you can find from Google.
The most important thing is this: Basil loves a lot of water and Basil loves direct sunlight.
Here is my method and I've done this more than once with great success.
1. Buy some good potting soil and fill an 8"x10"pot 2/3-3/4 full.
1-b. Yes. I'm saying screw those little plastic seeding cups.
2. Make a 3" diameter reservoir in the center of the soil approximately 2" deep.
3. Pour in organic basil seeds and cover with soil. Pack the soil lightly.
4. Lightly water.
5. Leave outside in the sunlight if there is no threat of a frost.
Continue to lightly water the pot every day for the first two weeks being sure not to over-saturate the soil. You should see the green within just a few days, and it's exciting! When the sprouts begin to flourish, begin adding more water and give it plenty of sunlight. If you water this plant every morning and leave it in the sun, it will go absolutely nuts! And I can think of a nut that goes quite well with basil... Vegan Pesto recipe for another day... It's GOOD.
To be more specific about a flourishing basil plant in direct sunlight, you can saturate the soil in the morning on a daily basis. Pull off leaves as you need for cooking throughout the Summer. The plant will continue to grow as long as it has enough of the two things that it loves the most. Hell, sing to it as well, if you like.
You'll be singing anyway.
Who the hell doesn't love Basil?!!!
