It's a bullshit argument based on false premises.
If Bitcoin becomes widespread enough that most people hold their savings in it, then it will greatly and permanently reduce liquidity in the financial system, lead to a decrease in consumer spending and cause major ructions in the global economy.
Looking on the internet I see that in the USA,
22% of the population has no savings and 44% could not pay
an unexpected 1K.So I don't even go into the rest. There are countries that are more thrifty than the USA, of course, but they are the exception rather than the norm.
You could have applied it to gold, which is much more widespread in the population, and has not led to shrink the economy (if gold becomes widespread enough that most people hold their savings in it, then it will greatly and permanently reduce liquidity in the financial system).