Yes, there are riders who are physicaly stronger than him on the endurance side (Vingegaard, Pogačar, maybe Remco, maybe some new talents soon). But a three week race is a lotery - like this Giro has shown (and many GTs in the past - Roglič would be one to know himself). Things happen to top favourites - they crash, lose time, get sick, are not at the level expected. Everyone thought Evans will never win the Tour against Contador and Schleck in their prime. Yet the planets aligned and he won at 34.
For Primož getting the Giro ticked off is a major stepping stone - if he wins it tomorrow (fingers crossed for no bad luck) then he can basically focus on the Tour for the rest of his career from here on in. And you never know when the stars align. Next year the Tour will have a slightly shortened copy of Tokio olympic TT on stage 20 - why not give it a try.
And concerning the team - I think Roglič is happy at Jumbo and the team is the best enviroment for him. Plus, imagine there comes a Tour where something happens to Pogi or Remco (if he starts) and suddenly Rog and Vinge are far above anyone else... I am not saying it is fair... but a Dauphine 2022 scenario could be on the cards.
Concerning his career - I don't think he should obsess to much with the Tour - if it happens it happens, if not, well it is not the end of the world. He should however try to win Tour de Suisse and Lombardia - two races well suited to him and those would really look good on his palmares. 4GTs (and counting), maybe 2 (different) monuments, all 7 stage races, olympic title... that would be quite a career! Plus he has said 100 career wins is a number he would love to reach. If everything goes according to plan tomoroww, he will be on 74 already.