The answer

I think I've found the answer to the question, why are some people rich and others poor?

I have this friend, he is rich. He used to work with this woman, who is also rich. They were both doctors, both on pension now. This woman's husband was a civil engineer, also on pension. But there is no shortage of money in either households. They are, in effect, billionaires.

Today is this woman's birthday. I bought her a nice gift, and wrapped it in nice paper. So, my friend makes her a card (just a photo printed on normal paper), and taped the "card" onto the gift, without an envelope. I was taken aback a bit. I mean, no envelope? His explanation: "envelopes cost money."

The joke is, she'll totally understand.

So there.

Take care!