agree too, many people just cannot picturing retirement at 45 even if they can afford to becos they have got nothing in their life except for work. Their life is progammed as such a "worker's life" who grinded day and night since their early days. You could also say their mentality is more of a "giver/saver" type , saving all resources and the best for their next generations/self security, placing less emphasis on self and never dared to pursue other things that makes them truely fulfilled, waiving it off as " aiyah, not practical, pay peanuts, not glamourous etc"
Hence without work they are at a lost with nothing much to fulfil, no social life, no subordinates to self brag to, hence going back to their jobs for a sense of self-worth.
On the other hand, those people who make such far-sight and enduring plans to retire early are highly likely to probably have also made plans for their bucket list to tick off upon retirement.
As you have said, Do what whatever they want without have to worry about money, and work not for the sake of money, they would even work for free so long they like what they are doing.