The top poster's wife is correct. Electronegativity is the key. It seems kind of intuitive, but very difficult to explain.
One definition is that metals can conduct electricity - as in exchanging electrons.
The periodic table is two dimensional. The vertical axis or rows tells how many shells or layers or orbits of electrons an atom has. As we go downwards in the table the exchangeable electrons are positioned further away from the protons, so the electrons are less attached and more likely to be exchanged by close proximity of other atoms.
The horizontal axis is the number of electrons in the outermost orbit. The rightmost ones have full outer orbits and don't have vacancies to exchange electrons, but as we go left, the atoms are more and more short of electrons to fulfil the outermost orbit = electronegativity= missing some electrons.
Combining this shows that the atoms most likely to exchange electrons are in the bottom left corner of the table, which is also the previously mentioned definition of metals.
Someone else pointed out that the actual distribution of atoms is very much not metallic. In the entire universe there is 73% hydrogen, 25% helium and only 2% of everything else including all metals. Even on a planet consisting of "everything else" very much, it's still rare to come by metals, hence their value.
The reason why metals take up so much space on the period table is simply that metals have a lot of different configurations which need to be described because they are different from each other.
Metals have what're called delocalized electrons, where electrons just kind of wander around a metallic bond between atoms. Metallic bonds involve a very low level of attraction between the nucleus and its electron cloud. Turns out most elements have this, so they do metallic bonding.
It's only when atoms start to get a little wobbly do they exhibit enough electronegativity to perform ionic or covalent bonding, where the molecules donate electrons. Electronegativity increases on the right side of the periodic table when electron valency starts getting lower. And that's the non-metal side.
So the answer is basically that you need more of an electrical charge to exhibit the things we've classified as non-metals. Metals are more chill and generally less reactive.
I should also mention that non-metals have a liquid/solid metallic phase at certain temperatures and pressures. I remember a Chinese study a few years ago claiming to have made metallic nitrogen.
I mean... What kind of answer are you expecting? We can't know why the universe is how it is, we can just observe that it is like that.
I mean why is the speed of light that specific value and not faster or slower? It just... is.
Your question is more philosophical than physical.
they get more and more electrons, which are weaker and weaker bound, thus form metals
Keep in mind our categories are pretty arbitrary. We have stuff like semimetals and so on. All bonding has multiple characteristics outside of extremes, e.g. covalent bonds with dipole character.
Metals are just our name for the broad category of bonding between extremes at conditions we usually find on earth where we live. They are soft squashy bonds that are kinda slutty because they're just sort of average.
Actually within the metals we see some pretty different characteristics, especially with D orbital chemistry stuff but because of inertia we just keep these things all in the same category of metals because shiny squishy was a lot more obvious than fucky wucky complexing when people named them.
Cause the laws of physics as we understand them selected for those configurations during and after the Big Bang.
I think that we have a perception bias towards things that interest us.
Since the elements in the top-right corner (C, O, N, P, S, Si, Fe, Al, Na, ...) are interesting to us, that's what we typically look at. And in that region, things are fairly balanced. It's only in the regions where we don't typically look, where we said "let's just make it all metal so the categorization is done, call it a day, and move on". I think.
It's more the case that in human interactions with the elements, most of them exhibit a metallic phase because we're exposed to the elements on Earth. Out in space elements do weird things. Gaseous clouds of gold, solid metal nitrogen. A lot of elements in the universe are in plasma phase, which isnt common at all on Earth.
Metals are metal on earth because their electronegativity gives them metallic bonds in our atmosphere.
Matter likes the shape that gives the property of metals to elements more than it likes other shapes, probably something like that
