If you're arguing to not have all investments in NASDAQ, that advice is good for any point in time. At least diversify to a total stock market fund such as VTSA

If you're arguing to not have all investments in NASDAQ, that advice is good for any point in time. At least diversify to a total stock market fund such as VTSAX and have an allocation of bonds to fit your risk tolerance. Maybe add some international equities as well. Diversifing is smarter than timing the market.