All we can tell from the pictures is that OP suggested 200k and then took a better offer instead. What is so wrong with that?
To me it seems like the two people saying they will report OP are just trying to take advantage of someone who isn't as aware of pricing especially when there's potential to triple their investment, they're clearing trying to rush OP into making a decision and when it's clear that OP isn't a native English speaker it's easy to become confused. It would be disgraceful to have this warrant a ban.
Why is going back on a deal something so frowned upon? It would be completely irresponsible to never go back on deals. You think a company selling a product would stick with a deal of $200,000 if someone else offered $600,000 for the same thing? This is exactly what's happening here, OP may have accepted a deal for 200k but then s/he was offered a much better deal and took that instead like any logical business model would do.
The people who only offered 200k to make a quick buck are the people that should be punished. Purposely low-balling is a much worse situation than backing out of a deal.