It's all in the dialect

I think some people forget that the word "fortuitous" has a semantic domain (implicit meaning) other than the meaning of something happening to one's advantage.  Nearly always the first meaning is that an event occurs randomly, by chance, or at the very least, not planned.  Nonetheless, some just use the word to mean that good things happen to them.

I would have to say the good things that have happened to me have been fortuitous.  Then again, I have heard people talk of the things that were planned for their lives as fortuitous incidents, which flies in the face of the two semantic domains of the word.  I think they meant fortunate, but when told that, they say they don't believe in fortune.  Things happen for a reason.

 Words truly are arbitrary in that speakers of a language have to agree on their meanings.  If there is disagreement, which happens more than traditional grammarians want to admit, then dialectal usage occurs.  Then there are two or more meanings in the dictionary for a word.

Trying to interpret the semantic domains for life is rather arbitrary as well.  Some people opt for one interpretation, others for a different interpretation.  So there pops up interpretations on what's best to do in life based on how people interpret events.  Take these two sayings, "Carpe diem," and "Good things come to those who wait."  Or these two, "The early bird catches the worm," and "Stop and smell the roses."  That leads to a dialectal difference in semantic domains in life interpretations.  That makes it as hard to understand someone else as trying to use the same semantic domain for the word fortuitous.

It's always interesting to see how people connect dots or interpret dialectal differences.