I have to imagine most men take their nails for granted. They get dirty, they get trimmed, they’re there, that’s it.
Playing a classical string instrument sort of requires that you keep your nails short. At least for us playing shoulder-mounted instruments, long nails prevent you from properly pressing the string down on the fingerboard. (Cellists and bassists have it a bit easier, as the contact is more on the pad than the tip, but you still can’t let them be too long.) Even though I haven’t played viola meaningfully in over 15 years I still trim my nails reliably once a week.
Painting your nails gives one a much greater appreciation of the work that your hands, and indeed your nails, go through each day. When our bare nails grow, you see the white increase, and that’s about it.
But paint them—like you would paint most things, with a primer, multiple color coats, and a clear—and now you have this tangible record of effort. You see the bottom edge of the paint grow away from the cuticles, showing you how clean (or not) the paint was applied at the edge. You notice the clear coat slowly erode away, the surface quality reducing in its enhanced gloss or matte effect. When the clear is gone, the color layers start to crack and chip. Hit something with your hand the wrong way and it will leave a seemingly indelible mark of its own, until the layers it struck fade away and take all evidence of carelessness away with them. This is not poor quality paint, but being repeatedly exposed to the elements, to hand-washing, to daily work, it will inevitably wear.
For us in the lucky majority of humans using our hands, and for those of us who have never had to sit ourselves through a multi-hour paint session being able to do little else but wait for the next coat, putting something on your hands with great care that then clearly demonstrates the effects of time and effort applied against it is a worthwhile thing to witness and absorb.