My approach here would be the same as for many other expressions I was having trouble with.

Reflect on ways to say it in Esperanto. Reflect on different ways to say it in English. Check a few good bilingual dictionaries (variation of #1) Check an English thesaurus, then bilingual dictionaries (variation of #2)

My initial impulse is to say simply maltrafi. There are some contexts where this doesn't seem to make as much sense, but in other contexts it doesn't make much difference.

Dictionary.com defines "to miss out on something" as:

To fail to see, enjoy, etc, something

Comparing this to the many definitions of "to miss" at the site, the difference is not obvious. One can miss a chance - and usually things you're trying not to miss are things you don't want to miss out on.

The bilingual dictionaries I checked (Benson and Wells) did not contain an entry for "miss out." The thesauruses weren't much help either.

At this point, it looks like there are two main choices.

Use maltrafi. There are many examples where this seems to mean more or less "to miss out" - here's one: Kelkaj plenkreskuloj en la vico instigis nin ne maltrafi la okazon. Use an expression based on the English defintion I didn't want to miss out on that.

Mi nepre volis ĝui tion.

It all depends, of course, on what you want to say - and how you decide to express your thoughts in Esperanto (rather than just translating words from English).