I will make an over simplfied metaphoric comparision\scenario, look at it this way, because it seems like, and I can see how so, but we all seem to be comparing bitcoin wallets and likes to bank accounts, when in actual fact what we should be comparing it to is your physical wallet with paper currency. If you handed paper cash to a stranger, its mostly final, non-refundable as you will probably never see that person physically again, so you can't get your cash back.
Think back also to when paper currency was also replacing precious metal coins, a lot of people would have been very sceptical of this concept. They would have wondered if the paper was really a representation of the precious metals, i.e backed by them (i'm only trying to paint a picture of the scenario here nothing else). So it's basically the mindset and shift of conceptual thinking.
Your grandmother can post pictures on the internet? well just imagine her when she firt saw a computer? she would never have thought of ever finding a use for it.
Now back to the paper cash in a wallet, if you went to a legal registered vendor like a supermarket, you could give up your papaer currency in exchange for goods, but you could get a refund if the goods were faulty( depending of the terms of the sale of course). The point I'm trying to make here is that you can do exactly the same thing here with crypto currency. So it needs to be thought of conceptually as simple physical wallet rather than a bank account. tow very different things. ( mind you I drastically over simplified how much more effective crytpo currency is here). So what seems totally nonsensical because of a change of concept will just become the norm, its just that there are no authorities enforcing this.