What you're talking about is using money to buy a commodity as an investment. If the currency WERE the commodity, and assuming a deflationary environment, working people would find they would have a decreasing share of the currency to begin with. In other words, the reason working people currently have enough money to buy BTC as an investment, is that they are using a non-deflationary currency.

Also note that buying stocks is only marginally more difficult than opening a bank account, and investing in major index funds via ETFs is almost as good as a term deposit (with minimal long term risk of realising a loss UNLESS you are forced to access the money at some time relatively soon after purchasing).

After you have created the account, buying more is easier than using a BTC ATM.

Given the risk of a) BTC going to 0 and b) being scammed and/or otherwise losing all of your BTC I'd say everday people are much, much better off putting their money in index funds.