Difference between "miss all the fun" and "miss out on all the fun"
1. I don't want to miss out on all the fun!
2. He spent a miserable day in bed thinking of all the fun he was missing.

Given above sentences, are "miss" and "miss out on" interchangeable?

3. It was an opportunity not to be missed.

For the third sentence, can we use "missed out on" instead of "missed"?

Question

Difference between "miss all the fun" and "miss out on all the fun"
1. I don't want to miss out on all the fun!
2. He spent a miserable day in bed thinking of all the fun he was missing.

Given above sentences, are "miss" and "miss out on" interchangeable?

3. It was an opportunity not to be missed.

For the third sentence, can we use "missed out on" instead of "missed"?

Answer

"Miss out" usually carries the meaning of "miss completely" or "miss, as a result".

It's not always possible to explain phrasal verbs in a technical sense, but adding "out (on)" does change the meaning a bit.

Answer

You missed out. Meaning, you weren't there, and thus got nothing. You missed out on all the food. You missed out on the free giveaway, and etc. Don't miss an opportunity. Meaning, beware that you may miss (not receive something you may want or need. Look out! Don't miss it! (A warning or admonition that you have to pay attention to something or receive a loss of some kind.)