- where in your career you were
- where in location you were
- what kind of employer you had
Far and away the hardest hit during the last crash were new-grads who had accepted job offers that hadn't actually started yet. Those jobs immediately went away and there was nothing to replace them with. I know of lots of people who left tech in general after this, and others who constitute a "lost" generation that has always made less money/done less interesting things because of this. Everyone up the experience ladder did better in an almost exponential way. That is, junior devs either spent a lot of time unemployed or accepted jobs at salaries well below what they were expecting. More experienced devs ended up hunkering down in "boring" jobs and saw their wages stagnate for a few years etc.
SV and the west coast in general got hit much harder than the rest of the country. NYC, Chicago, Texas, Minneapolis, Atl, etc had down cycles but their diversified employer base meant that it was muted by comparison.
Besides the obvious dying of unsustainable startups and their employees, the people in tech. services were much more impacted than other industries. Particularly hard hit, were body shops and the big consultancies. Finance, insurance, pharma, etc all took much less of a hit.
I'd add that along with the dot com bubble, several other factors added in to make the last crash particularly brutal. Lots of enterprises used the 2000 bug scare as an excuse to retool and there was tons of work that went away after that ramped down. Then 9/11 came along and put a major hit on companies willingness to spend on infrastructure.
As far as being "well-insulated", there isn't much advice to give. These are macro factor trends that impact everyone. The advice for this is the same as for dealing with any risk. Keep your spend rate low, have a safety net, diversify your skill set and have a strong professional network that thinks highly of you.