If you think 1 BTC will be worth $1 million in the future, would you use 1 BTC to buy a car thats priced at 10k today?
If you have $10K today, would you use it to buy a bitcoin or a car? You have no idea how far in the future that million dollar bitcoin might be, but you definitely know whether you need a car
now. And if you start to save up another $10K by working a better job that your new car takes you to, bitcoin might tank any number of times, giving you buying opportunities. Ultimately, you have to balance risks and opportunities.