what would motivate anyone to switch from performing shares to underperforming btc?

nothing

btc is a transparent trackable coin, same as cbdcs.

there is no difference except the theoretical confiscation which will never happen in normal countries.. only in communist dictatorships like communist eu, venezuela, cuba etc.

the only motivation to buy btc would be the useage as a currency, to replace the broken bank. all it needs is privacy and fungibility