Not to go diving too far down this particular rabbit hole... but the bolded is a major point of variance for people. What doesn't make sense to one might be completely understandable to another. And some people will latch onto something that they don't immediately understand, and rather than trying to understand it they will assume their lack of understanding means that it fundamentally 'doesn't make sense,' and therefore something else must be up.
So a person's baseline understanding of certain issues, couple with how quickly that person can go from trusting to skeptical has a lot to do with whether they entertain alternative possibilities, and to what extent.
That's specific to marijuana. The PED policy was made more strict than it already was. First positive test for anabolic steroids is a six game suspension now; was previously four games. I believe HGH is treated as an anabolic steroid by the PED policy.
And teams cannot suspend players for drug violations, only the league can. A team can suspend a player for conduct detrimental, but if that's related to a drug violation, it will be challenged and the team will (most likely) lose.
From the moment Hasselback patted Luck on the chest...nothing about the Luck saga has been common. The secrecy...the misleading of fans...the incredibly long rehab...the Europe trip...the sudden retirement...all of it.
At the time of the retirement, he had been dealing with that weird ankle/calf issue for at least two months, and it wasn't going away. He could have felt like he would have to use painkillers to make it through the season. Or with the uncertainty of what it was, maybe he was considering surgery, but knew that would come with significant pain during recovery.
A year or two later, the leg issue could be gone entirely. So the immediate conflict related to managing pain is no longer there.
I agree with you though, it would be naive to assume that any NFL player could play without experiencing serious pain. However, in March of 2020, the NFL's testing policy for marijuana changed dramatically, to the extent that it's now basically a viable option for pain management. If a player isn't already in the drug testing program due to previous positive tests, he basically only has to worry about being randomly tested during a small window at the start of training camp. And the penalties for a positive test no longer includes a suspension.
So if that were a player's preferred method of pain management, the new policy makes it a lot easier to get by.
Now it won't be an issue. Per the current CBA players can no longer be suspended for failed drug tests, they can only be fined.
That is by the league. I don't know if the teams can then suspend a player or not.