When you're 83 and your kid is my age, he'll probably wish there was anything he could do to make you 20 years younger.
I'm not saying you shouldn't have had a kid, or anything like that, but I don't know how you can suggest that it will never be a problem that you are a relatively old father (versus if you had kids in your 30s, other things being equal, which obviously they aren't).
The average life expectancy for a male in the USA is 76. All other things being equal, a 51 year old father will die when their offspring is 25 years old. This is too early to lose a parent. Think about how this would have effected you, reader of this post. This is also assuming that the father does not experience any debilitating illnesses prior to dying, such as dementia, which would place an inordinate burden on a young person, who would have far fewer resources and life experience to draw on during such an ordeal.
These are not small potatoes. Think before you act, be responsible. You’re gambling with someone else’s life and wellbeing.
And maybe taking care of a parent with dementia is actually more of a problem when you're older and have kids of your own?
At my advanced age, I have the advantage of remembering things like the arguments you would hear back in the 1960's about why interracial marriage was a bad idea. Not because we're racist of course! But think of the practical difficulties. Like, the kids won't fit into either community! I'm sure you can think of more reasons too.
The later the better.
> And maybe taking care of a parent with dementia is actually more of a problem when you're older and have kids of your own?
It would certainly be easier to deal with when you have more stability in your life and are more emotionally mature.
> At my advanced age, I have the advantage of remembering things like the arguments you would hear back in the 1960's about why interracial marriage was a bad idea. Not because we're racist of course! But think of the practical difficulties. Like, the kids won't fit into either community! I'm sure you can think of more reasons too.
Do you really think this is a reasonable comparison? Of course you’ll say that you do. It’s not.
The fact is that every kid comes into the world with some advantages and some disadvantages. Any disadvantages from having an older parent are at most on a par with the disadvantages from not having particularly wealthy parents, or not having parents with perfect genes, or having parents who were abused by their own parents, or having parents who aren't citizens of a first-world country, and so on and so on.
In reality, you may be 51, and may be in a good position otherwise to have a kid, and the question is whether being 51 is a reason not to. And the answer is "no", it is not. Not unless you also think that other people with non-major reasons not to have a kid shouldn't. In other words, not unless you think nobody should have kids.
People who are no longer young should simply ignore this sort of advice. Unless you're in (seriously) poor health, just go for it.