Yes the high yield bond fund is probably a better long term choice because it pays a lot higher interest rate. The only problem would be if you need that money sometime very soon. In the event of a recession, the high yield bond fund would likely crash (much like the stock market). Chances are the fund would eventually recover again as the bonds mature, but there could be some years where you are sitting on a loss.

Over the long term though (10 or 20 years) the high yield fund should have no problem blowing away the money market fund. Over even longer periods of time (30 years or more) stocks are probably an even better option.

Of course I don't know the specific bond fund you are talking about in this hypothetical scenario, and I couldn't provide any specific recommendation without reading the fine print first, however in general - a high yield bond fund is going to do better than a money market over the long term. If you need the money soon though (less than 5 years or so), it might be smart to set some aside in the money market for a rainy day.

Suppose somebody has $240,000 in a money market paying less than $2,000 a year.

Suppose they also have $155,000 in a high yield bond fund paying almost $10,000 a year.

Let's see - $240K paying less than 2K. $155K paying around $10K. Something wrong there - the $240K isn't making much at all. What would you advise them to do?