There are two sides of this, first how believable it is, and second, how likely Everton would be to take such a deal.
I really do not consider this report very believable. If we scan the teams interested, Atletico does not usually show much interest in wingers who do not defend at all and cannot really pass.
Chelsea just spent a club record fee on Christian Pulisic, PSG does need to replace Edison Cavani but it seems unlikely that Richarlison would be the right tactical fit to go there, and Milan would have to smash their record arrival fee to give Everton a meaningful profit on the Brazilian winger.
Now, as to whether Everton should actually consider selling Richarlison. Objectively speaking, £80m is more than enough money for this quality and services. He has significant limitations and needs a very specific team structure around him to be at his best. He’s a very, very, talented player, but that reported asking sum is massive.
However, the equation on whether Everton should consider selling him is far more simple than that. In my opinion, it breaks down simply to this: If you intend on continuing with Marco Silva, you essentially have to keep Richarlison unless someone is willing to pay an absolutely astronomical figure. Silva has tied his career to the Brazilian, making him the focal point of his offense at his last two stops. Everything he does runs through Richarlison, and Silva stuck his neck out for him this summer (which has more or less paid off in the winger’s goalscoring record.)
Those who are so fed up with Everton’s set piece zonal marking and thus want Silva gone will have no great argument from me. I absolutely get that. I would prefer we have a little more continuity than that and simply make sure we hire Silva a set piece assistant, but both sides of that debate are understandable to me.
If you want Silva to stay, you’ll probably want Richarlison to stay as well. If you’re done with the Portuguese, you are probably okay with the Brazilian going.