In simplistic terms the reason this accident happened was the reluctance of the pilot to turn back and wait for the weather to improve.
Given his lack of night flying ability he should never have taken off.
They could have night stopped in Guernsey or Jersey and and arrived in Cardiff the next day.
The same applies to this accident .
https://www.bbc.co.uk/news/uk-england-46820519
Gethomeitis.
No Monday job is worth dying for on a Sunday afternoon.(Or in this case a Thursday morning)
Running out of fuel, taking short cuts across high terrain, getting caught in severe turbulence,or just entering cloud without qualifications or experience are all simple reasons why we consistently see intelligent people killing themselves.
It is all down to planning and pilot skills.