Infuriating experience as an attempted buyer

I have been actively searching for a ZJ/WJ Jeep Grand Cherokee for a few months with a few needs. Be local to me, unmodified and under 200k miles. Already I am searching for a unicorn.

I found one within an hour round trip of me, 177k miles, unmodified and in great condition (according to the pictures.)

I messaged the seller with a few basic questions, gave him my number and let him know I am a serious buyer. It took him days to respond. He answered a couple of the questions but went silent. I sent him another message and asked if he could give me a call and we could discuss the vehicle and set a date to meet. I told him my days off and when I could see the vehicle, again radio silence.

Days went by and I woke up to a message today "I'm looking for a car, still don't know if I am actually going to sell this one. I will keep you updated."

Why are people like this? Is it unrealistic for me to anticipate you are selling your vehicle if you post it for sale? I was willing to pay him what he was asking, no negotiation or tire kicking. Am I in the wrong?