So you'd rather ride the sinking ship and lose all your money as the company goes bankrupt? Are you saying you'd never exit any of your positions no matter how much money you lost?
The stock market cannot go to 0. It is literally impossible. If you are invested in the fortune 500.. and the value went to literally 0.. we are in a zombie Apocalypse. Money no longer has value. So yes I lost all my investment, but I also don't have a job, and a gun is my most valuable asset.
Buy and hold = Buy big index funds (i.e. Fortune 500), and then never ever ever ever sell, until you are ready to spend the money (i.e. draw-downs in retirement).
Trying to go "oh the market lost 20% this week, it is going to 0 soon" is a fools investing.
The market itself cannot go to zero, but individual stocks can. If you're of the view the market can't be beat and investing in index funds is the way to go then your position is fine. If you're of the view where you select the stocks you want to invest in, as a great number of market participants are, then your position if flawed because stocks do go to 0 and as such exiting losing stocks makes sense. Tossing all your money into an index fund is not trading, so you're not even talking about the same thing I am.
Flash crashes massively hurt people who invest in particular stocks because they do often have exit points which get triggered by those crashes. The advice you're giving doesn't apply to these people, they're not the ones just dumping everything into an index fund.
