I haven't read anything or saw all the devante video, but my understanding was we low balled him and he was insulted.
I always kind of chuckle when "he was low balled and insulted" is the narrative for a player leaving a team. If a player is insulted by the failed negotiations, then said player doesn't understand how negotiations work. A team will have a bottom line number and if the player and his agent won't agree to it, time to trade/cut said player. Then there is the possibility that said team and/or player are just ready to move on from each other, whether it is one or both of them wanting that. Jordy Nelson was an example of that.
I also think high end players are often sitting in a position of great advantage. There is no doubt in my mind that their agents have been "quietly" shopping their player with other teams. Finding out what those teams would be willing to pay for said player. All those other teams, really wanting said player are bidding against each other and a good agent will let them know their "offer" will need to be higher. Once that high figure is found, with a team the player wants to play for, the agent and his player know where the current team has to go with an offer, to keep the player around.
The other disadvantage to the players current team, once negotiations cease and it has been decided that the player will be traded, is the agent saying "these are the only teams my guy will play for, make a trade happen with them."
Anyone doubting that Davante Adams didn't have a deal ready to go with the Raiders, BEFORE he and the Packers stopped negotiating, aren't seeing the big picture. The Packers had placed a value on Adams, Davante and his agent placed a value that the Packers would have to meet before he would stay. Guessing that "value" might have even been higher than what the Raiders offered, since Davante wanted to play for the Raiders and with Derek Carr.
"Oh they low-balled me" is a players way of trying to save face with the fans and media. When in reality, the team's value for the player was less than what others would pay.