There are different ways by which we can obtain bitcoins like Buying on exchange, accepting bitcoin payments or using mining.
Which is the fast and beneficial resources of obtaining bitcoin??
If you have the fiat the fastest way is to buy bitcoin. If you have marketable skills, then earning money and then using it to purchase bitcoin is reasonably fast (pretty similar to getting paid in bitcoin). If you have products to sell, maybe you have a farm, or a manufacturing plant, you can sell them for fiat or bitcoin. Mining will require miners which will require money to purchase and to pay for power.
The short answer is: what is the fastest way to earning money unless you already have money to invest.