Recently, i read on certain news where Michael Saylor stated, " I invested what I can not afford to loose".
This is good and works for educated people like him who are strong holders. It does not work for retail, who start panicking after Bitcoin drops 5%. A common sign of a retail investor is someone who buys high and sells low, so this approach is not for them. They should stick only to the old invest how much you can afford to lose.
I do not see anything wrong with investing what we can afford to lose. This simply reminds us that there is always risk involved in investment. There are cases where investment flops so investing what one can afford to lose in an investment that flops saves him a lot of headache since it will not affect his daily lives financially.
Another thing is investing all we have can end up in not a good situation where we are forced to sell at a loss when needs arise and the money in our pocket isn't enough for these expenses. Everything should be balanced and carefully planned. So investing in what we can afford to lose is always a safer approach to anything that has something to do with finance. Btw, my answer to the title is no, the concept of "invest how much you can afford to lose" has never changed.
The poster is talking about what Saylor wrote, so you should see into that and why he says that.