Because I want to save value in hard money.

Because I want transactions to be at the speed of light.

Because I don't want banks censoring my transactions.

Because I want transactions to be cheap.

Because I want to verify the transactions myself.

Because I want to have privacy with my money.

Because everyone can use this money all across the world, so people in poorly developed country's have finally a chance to save and build something for themselves too.

Because the cantillon effect doesn't apply to Bitcoin.