Why do guys ignore my texts and leave my messages on read?

When they send me a video or a photo, I acknowledge it. I comment on it, and even if I don't have something to say, I emoji like it or something. Not every man, but most of the time, i send stuff to a guy that I thought was funny, or maybe he'll think it's funny or something he'll find interesting. I took that time to also think about you, what could also make you smile, but then got left on read.
Either that or they just go on to the next subject like i didn't send anything. In the past, my ex told me I could stop sending him stuff and texting him so I don't like sending stuff constantly anymore. When I try and get no response, it feels like im more of a nuance, so I don't call or text first anymore. I don't like feeling like that, or my time is being wasted. Even before that, a guy that I was only texting at the time but planned to meet up with texted me that he wanted to sleep with me, but i was so boring over the phone that he changed his mind. That was before I learned you can send more than pictures, but im coming from bad experiences texting, and it makes me very reluctant to try.
Why do guys ignore my texts and leave my messages on read?
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