You have to use the spelling “J’aurai”, no s in the end.

Here, the tense and mode are different from what you suppose them to be. You are dealing in fact with the “futur antérieur de l’indicatif”; it is used here to express a nuance ;

• récapitulation, bilan, ironie, indignation, surprise, regret, ironie

encyclopédie libre, BDL

This turn is used frequently; none of the four sentences are proper as possible equivalent; here is a possible rephrasing;

• Ça m’a pris malheureusement dix ans pour m’en rendre compte, mais ça en vaut la peine.

It seems that regret on the ground of the long time needed is the main idea.

There is in French a notion of “futur dans le passé” (future in the past). This is a use of the conditional to convey something future from a past point of view.

1) It works for a simple futur:

Je te promets que je t'aiderai (present sentence with a future)

put in the past, it becomes:

Je t'ai promis que je t'aiderais. (notice the conditional)

2) It also works for more complex constructs. For the asked sentence, let’s start with something easier:

J'ai mis dix ans à m'en rendre compte, mais ça en vaut la peine. is a sentence in present tense, with a passé composé. Its meaning is rather straightforward.

J’aurai mis dix ans à m'en rendre compte, mais ça en vaut la peine. is a sentence in the present tense, with a futur antérieur. It adds a nuance of “récapitulation, bilan, ironie, indignation, surprise, regret, ironie” as explained by LPH.

And finally, your sentence:

J’aurais mis dix ans à m'en rendre compte, mais ça en valait la peine. is the same sentence, put in the past.

Note: To be complete, though not related to the question, if you start with my first sentence, not adding the futur antérieur nuance, and put it in the past, it becomes:

J’avais mis dix ans à m'en rendre compte, mais ça en valait la peine. (with pluperfect)

This is basically a mistake. The proper tense that should be used here is futur antérieur, which spells “j’aurai mis”. Here it is indeed spelled as a conditionnel, which is a rather common mistake, unfortunately.