I think the 5% odds are an underestimation, because Carlsen will change his focus now and won't spend time preparing for the World Championship. He will likely also prioritize risky wins vs safer draws.
> He will likely also prioritize risky wins vs safer draws.
It seems kind of unfair that this is the strategy needed to increase ELO. If the safest strategy to guarantee a win in a tournament is winning a single game and drawing the rest, then you shouldn't be penalized for that in your ELO, versus playing risky and winning more but also losing some.
It's not the strategy needed to increase your rating on average. It's the strategy needed to target high variance in search of reaching a far-outlying value.
Considering there are quite a few players from young generation who reached 2700+ recently I don't see him reaching his goal and even 5% looks optimistic.
Problem is new generation probably are less affected psychologically against him and I suspect Carlsen has higher. risk of losing against them compared to old guard.