Do we ever say to someone who wants to start a business 'don't invest what you can't afford to lose'?
No.
Why?
Because, apart from the wage slaves, we all know that 1 successful business is all it takes to be set for life. 'Go for it' is our message, apply all your energy, time and capital to it. If it does not work out, well you can try again later in something else. You'll learn and will nail it sooner or later.
So why does this not apply to investing?
I'm not talking about those that already have considerable capital. Ofcourse it's not wise then to invest it all in your startup, and equally unwise to invest it all in one investment.
But if you don't have a lot of savings/capital it makes sense to go all-into bitcoin. Just like it makes sense to deploy all your capital to a startup.
So to the not well off yet & brave, I say: go all in.
If bitcoin works out it will hundredfold from the current $100 to $10,000 in +/- 5 years. If you succeed in deploying $10k, that's $1 million you've made.
Once u have a few 100k you can start to apply proper risk management and diversify but until then you will need to concentrate in order to make it.
This is not investment advice, just an opinion. An opinion very different from my original one.