You don't know much about making bets either, do you CynicalBear?
The person offering the wager is the one who chooses the wording of the wager. The wording is right there in the open, not hidden, or "based on deceit". That assertion is completely false.
If the one to whom the wager is offered does not like the wording of the wager offer, they can change the wording, and offer the revised wager back. Or, they can make a completely new wager offer. Or, they can just refuse to make the wager.
I also never claimed that "at" is synonymous with "on". That is another horrendous falsehood.
The English statement "There is CynicalBear on his rocking chair with his family", could validly mean that the whole family is actually on the rocking chair with CynicalBear, or it could also validly mean that the whole family is there in the room with CynicalBear, who is on his rocking chair. People with common sense can figure out which meaning applies in that situation, based on the context.
People who do not grasp this simple difference, just do not understand the mechanics of the English language completely.