What makes a watch collectible?

i didn’t want to piggy back onto someone else’s thread by posting too much off topic stuff. But here is the watch. 1908 model, 16-size, 21-jewel, Waltham Crescent Street in a nickel alloy case. Rough dial. Original owner bought it in 1918, so it is 104 years old. It was his only service watch over a 44 year career with Canadian Pacific Railway, as a firemen and a locomotive engineer. Serviced 33 times by the same watch inspector, and I have a complete breakdown of all those repairs as to date, and what was done.