Exactly what the title says.
If bitcoin dropped to the price of a dollar (which we hope it never will), what would you do? Buy more and hold, sell? Buy a promising altcoin like ETH?
I personally would buy more bitcoin.
i would buy 20 bitcoins and would let them sit in my wallet, as i am pretty sure that even if bitcoin price would drop so low, it's price still would rise back up some day
Why only 20 bitcoins? That would only be like $20

If I do, I will buy a minimum of $1000 or 1000 bitcoins and just set and forget it for a decade - not minding anything about bitcoin news and stuff like that. If after a decade the price will go even just $100 I'll be $100,000 richer but if the btc price goes $1000 each, I'll be a millionaire then, right?

But bitcoin is not something you can forget about for 10 years. Because if most people do like you, then bitcoin will simply not exist anymore. It needs users, it needs miners.