Tell me a concrete reason why I should every buy a bitcoin. Ever.

I get paid in dollars. I put the dollars into a bank. Zero transaction fees to do that. My monthly bills are paid automatically from my bank account. Zero transaction fee to do that. I have a credit card (electronic cash) that I can use anywhere in the world. I pay no fees, the merchants pay the fees. I get 2% cash back for using the card. The balance is paid automatically every month from my bank account. No transaction fee for that. I can buy whatever I want online using my credit card and if I have a problem, I can dispute the transaction and reverse it. Transactions are immediate.

I don't have cash under the mattress. I have stocks, bonds, real estate. None of those are dollars, they are priced in dollars.

So, since you believe in the technology, tell me why I would ever want a bitcoin.

And no, I am not worried about the "value of the dollar" because as I stated, I don't have dollars under the mattress. I have stocks, bonds and real estate. I don't hold dollars as an asset (and neither does anyone else).