With both old and brand new you can build a nice collection and above all have a lot of fun. In musical instruments, the phrase "Vintage" is used "at all times". Originally, that term actually refers to the vintage ("Vin" t - "Age"). But when is something actually "vintage"? Some assume this is 25 years or older, others just want to say: "old and still original". But also your new purchase will automatically become "antique".
I regularly get the question whether old is better than new. Take a look at the various discussions that can be found on the internet about this, I do not think this site is the right place to add much. I understand that someone with a 1959 Les Paul, for example, is very enthusiastic about his Gibson, and may never have had a better one. But that does not mean that all 1959 Les Pauls are comparable and that a new instrument is always less by definition. In addition, one may wonder whether you can easily drag a guitar of several tens of thousands of Euros to the rehearsal room every week and then use it on stage with confidence. A lot of money is involved in trading such top instruments, with the risk that you will end up with a "counterfeit".
The fact that a copy is still in its original condition is certainly appreciated in practice. It is easier to find an interested person for a guitar with hardly any paint (if still original) on it than for a similar instrument that has been completely repainted. An adjustment that cannot be reversed is therefore often an "assessment" of the value.
I can imagine that someone wants to focus on a particular brand, a specific period or a special type of instrument. I once ran into someone who was only interested in red copies.
The advantage of a defined focus is that you can build up a lot of specific knowledge. For example, if you focus on a certain brand or model, you will get enough specialism after a while to quickly estimate the value and originality of each offer. In any case, it is advisable to orient yourself properly for every potential purchase. The internet is the way to do this.
Keep in mind that defects may come to light afterwards that have escaped purchase or that you might not have seen at the time. In this way, the costs can increase unintentionally. I myself have the convenience that I can adjust an instrument or repair a guitar or amplifier myself.
The interest in the somewhat older guitars must arise from a piece of passion, perhaps it is emotion or nostalgia? However, it seems that more and more collectors are emerging who see it purely as a kind of investment. Fortunately, they mainly focus on the exclusive market, which mainly concerns rare versions or objects in which the original owner is / was a celebrity. The amounts involved are such that an average enthusiast would not intend to spend it.
