Here on HN, you might be surprised at the range of backgrounds people come from. There are people from all over the world. It's a startup forum, so it attracts "indie hacker" types, entrepreneurs and bootstrappers of all kinds vaguely tech related, and people whose IT interest is primarily open source, not just well-paid salarymen.
By "a lot of assets" I mostly mean "a house", but a decent size pension would count instead. Both are out of reach for many people now.
I agree that most old people in the developed world don't end up homeless.
On the other hand, there's a growing economic housing crisis affecting a lot of people in almost every developed country. Mostly affecting (current) younger people, and most (current) older people are almost oblivious to it. It's working its way up the age range. This is new.
You cannot assume what worked will always work, when there are factors that appear to be changing across generations.
Many people are paying >50% of their income in rent, and rents are still rising in most places faster than incomes. Most renters cannot find a way to get on the house buying ladder. If things carry on as they are, many people currently young will retire while renting. If you're paying 50% income on rent now, what are you going to do at pension time, as pensions are typically 1/3 or less of the income prior to retirement. You'll have to carry on working, but that gets harder with age, faster for some people than others.
I agree with you most will probably not end up homeless, but the point is, for that to work out, something will have to change.
I personally know an IT person who reached retirement age and is dependent on state benefits to pay their ongoing rent, and found those state benefits enough for almost zero properties in the area they lived for decades prior, making it hard to find a place from which to continue looking after their own older parents. They struggle, and have to work on the side.
And another, skilled and knowledgable software engineer, currently paid well, who for a period last year was unable to pay for rent or food due to running out of money and access to credit. They needed help from local volunteers just to eat. How can that happen, you may think? This is HN, where not everyone is working for a company. Like many HN readers who are entrepreneurial (it's notionally a startup forum), they were a business bootstrapper, and it's easy for that to become financially precarious when things don't go so well. Add a badly timed pandemic into the mix, government support for everyone except small business owners, and a time where jobs were not proving easy to get, and you have a recipe where homelessness really was realistic for a skilled IT person and, unfortunately, their family. I'm sure they're not the only one around here who's had to seriously face it last year.
My own pension is projected to be less than my current rent, which is already low for the area, so I think it's rational to be thinking about that.