Bitcoin works regardless of the price. There is nothing to worry about, even if it drops below $1.
Sure, it might still work but where is my $70,000 that i invested?
When you deposit a paycheck into your bank account do you consider that an "investment" in dollars?
Bitcoin is not an investment. It is money.
Bitcoin is very much an investment right now. It can be used as money the same way you can trade an ounce of gold for some item, but gold is not money and Bitcoin is not money. It could be in the future (gold used to be money) but neither are right now.