Besides, how is it possible that when there are assets and sudden needs, we do not cash them. For me, BTC is an investment vehicle if I want to hold or sell it, of course it depends on my financial condition.
There's no such rule preventing you from cashing it out, but at least you can engage properly with better cashflow management techniques. It's important that you build your emergency fund alongside your accumulating BTC, so that when such unplanned need comes out, you attend to it with your emergency fund.
But in the occasion that it outweighs your emergency fund, maybe shaving parts of your portfolio could help you solve your problem. All dependence shouldn't be on your Bitcoin portfolio for you to have a meaningful investment activity, else you might end up losing considerably when you sell at a price lower than your buying price and might not even reach your accumulation target.
The key is to manage your discretionary income properly and set up emergency funding and variances of backup funds from it in order to protect your Bitcoin portfolio from constant attack when needs present themselves.