Enable segwit with no stupid hardfork drama, and see bitcoin skyrocket.
Break bitcoin in half, see the price crash, and see everyone involved in the forked chain going bankrupt, with the price going to 0 on Forkcoin, and with Bitcoin crashing but going back 3 years in price and taking another 3 years to recover.

And that's based on which past events?
Ethereum forked and didn't need 3 years to recover, it actually pumped and botch chains are worth more than before the fork.
Litecoin activated segwit and is worth much more than before.
Stop making up shit and trying to scare people.