Marcus Aurelius, as all the Stoics did, practices thinking of fame and high office as something to be put in its correct place, rather than something of importance. Even ambition itself to them is seen as something to be avoided. Why is ambition seen as good in our society now? Presumably, it was in Roman times too, which is why the Stoics had to practice avoiding it.
If you are an ambitious male, it is probably an attractive trait to your partner. Can you work towards anything in the future without ambition? If we are to despise the future and embrace the present, then surely, we would never even move from our current place of rest.
It is easy to see why courting fame should not be seen as a good thing. All your freedoms will be gone. All your money wasted in the premiums of privacy just to get the same liberties as anyone else. Paying thousands per night for a hotel room that you are then trapped in. Unable to go to the shops to get some mil without being pursued.
But what of more noble ambitions? What of calling? Marcus also laments of himself being lazy staying in bed. If he has no ambition or ambition is bad, then why is staying in bed so bad? Is working towards something bad? The work itself is in the present. Only taking the mind too far into the future is undesirable as it takes away from actually doing the work.
Great ambitions, those that run away with a person, to win at all costs, those are easier to see that they should be avoided. But to want to be the best version of yourself? Surely there can be no better ambition. The only better one perhaps is to help others as much as possible but to do that we must look after ourselves first.