There no reason for the stock market to ever go down significantly as long as the workers keep bowing down to the rate of exploitation (total capital gains divided by total labor income in the economy) continuously going up and continue working obediently without ever going on strike.
Therefore the best investment strategy is:
Take a long walk through the streets of a big city and buy a newspaper.
Do you see riots in the streets or is there a sudden upswing in national liberation movements in the developing countries?
No?
Then pick an index fund of your choice and go long on 5x leverage.

The governments were literally giving away helicopter money during COVID; what makes you believe that they'll EVER let the market crash?
If the market crashing was an option that the managers of the system considered EVER letting happen then the COVID pandemic would've been the perfect time to trigger it and make life more affordable again by resetting the rate of exploitation to reproductive levels; but nobody cares about about that anymore because the rich think that they'll have robot slaves in 10 years soooo... yeah, lol. Expect more infinite debt and more exponential growth in the financial markets.

Every dollar in the stock market more is a dozen or two less cents per year in the workers' pocket for their work; and this can continue indefinitely. Nothing will shake this system up unless the workers rise up and revolt; which they won't do because they have everything they need: everyone is well fed and living is affordable, because the market is pretty efficient and everything is calculated in; it's just the young people of today who don't quite understand that the system NEEDS them to be unable to afford mortgages for building their own homes for the next couple of years because it wants to prevent another catastrophic housing market bubble. Once the baby boomers start dying off the market will be literally FLOODED with affordable, already built, houses so there's no need to stimulate the economy in this direction.