At the current difficulty, it takes about 500,000,000,000,000,000,000 SHA-256 calculations to earn 1 BTC.
If it takes a person 5 minutes to compute a hash and you want to earn 1 BTC in a year, you will need about 5,000,000,000,000,000 people. Unfortunately, that is about 700 thousand times the population of the planet.