Investing your life savings into Bitcoin is borderline retarded and indicative of a low financial intelligence.
That statement is so true it hurts.
So what do you think is a safe/good amount of your savings to invest in Bitcoin? 20, 30 over 50 percent?
The key here is it all depends on how much savings you've got. Most people I know have life savings of less than a year's salary, and don't own any assets. For them, it would probably make sense to invest a lot, >50%, because they could make the money back by living very economically for a few years.
If you have a million dollars in the bank, then it would be pretty dumb to invest >50% of it IMO, I would say no more than 15%, more like 5%
But if you have a million dollars and own 10 houses worth a million each, why not invest 100% of your money? If it fails, sell one of your houses and you'll have your money back.