"wear a helmet until you are comfortable with whatever wheels you are riding" sounds like a formula for "die on a bike once you've hit the dunning kruger effect"
Rent is still less than 1/3 of post tax income most places if you have a high paying tech job. Also you can always downsize on stuff to save on floorspace.
This both oversimplifies the experiences of people who have been through economic cycles before (some of them are shocked too), and underestimates the power of the human imagination. I for one believe I can read about an era I didn't experience, use my imagination to think about what it would have been like to live during that time, and if something similar happens in my lifetime, be less 'shocked'. I think many people can do this too!
Followers of Krashen know that it's sensible input that results in language acquisition. Duolingo gamifies the frequency of sensible input. Therefore Duolingo will work if frequently and consistently used. Fluent is an outdated term. It probably takes about six months to achieve any lasting result. Illusion of progress is impossible to prove or disprove probably.
A deliberate practice environment has four elements:
1) Repeat exposure (aka volume of attempts)
2) Valid environment (a win is a win and a loss is a loss)
3) Timely feedback (you know immediately whether you won or lost)
4) Deliberate practice.
Deliberate practice without the other three is not complete.
The Anti Cramer portfolio is not a sufficient contrarian approach, because the Cramer portfolio also underperforms similar to a random walk. Put another way, the opposite of a random walk is another random walk.
I think the bias against Leetcode is not specific enough. My bias against leetcode: stop screening at leetcode easy/medium. Screen instead at Hard/Extra hard.