First you have to build up your Bitcoin and that is can you do with a signature campaign or trading and last step it selling it for a high value.
Buying and holding is the simplest way to earn money from bitcoin, but if you really want to earn then you can offer services as you don't need to invest any money into it.
The sign of price increase rapidly is because of the law of supply and demand, since most of us think that halving will going to be profitable, so many now are holding their bitcoins tendency the supply of bitcoin becomes lower and the demand is becoming higher and the price becomes higher too.
That's why you can really earn by holding your bitcoin.