Why do people read messages and not respond?

[NcFcSc]

When they sell things on FB?

My son has asked for something for his birthday and I found 2 on FB. One I messaged and it was sold, the other said I was 2nd in line and he will let me know if its sold in the morning.

I can't find another of these items as there was one on amazon but I didn't realise it was from the USA and wouldn't arrive in time now.

I asked this morning if it had sold. Read and no reply.
In the afternoon I sent another message asking if the person had shown up as planned that morning. Read immediately and no reply.

Then this evening I send a 3rd message profusely apologising for messaging again and explaining that I'm really quite desperate to find one of these items and if its sold could he please let me know so i can try and source another (he is in my town so this is the best chance i have as theres no other ones locally so i will have to take my chance online and hope postage is fast!)

Again read but no reply.

This item is a few hundred pounds so I don't understand why he is reading but not replying. If its sold can't he just say so? It takes 3 seconds to type SOLD :(

You have my sympathy, it’s so frustrating.

We had similar happento us once. Back and forth messaging over a day or so to arrange collection time and address. The person then left us sat outside their house (or what they said was their house) and opened but ignored all messages on Messenger to say we were there to pick up etc.
It was a block of flats so unfortunately couldn’t just go to the front door as we didn’t even know what the number was, she said she’d meet us outside but no showed.

I still find it so weird to communicate back and forth to the point you have exchanged addresses and THEN decide to disappear. Bizarre.