It is absolutely so that a person without ambition or training will fall increasingly behind someone of equal talent who has dedication and good training. While the latter is maximizing and energizing their talent, the former is minimizing and ignoring theirs. There may be some point beyond which the talent dries up like an unwatered and unfertilized garden; whatever that unique creative energy is that can generate belief and express it through plastic form simply flickers and dies out from neglect and the pursuit of other interests in life. (Depression, illness and heavy responsibility can also all destroy that ability. )
But if there is that ability to obtain that belief state, it is quite hard to hold it back from expressing. This is the problem with your premise. If the artistic impulse is there, it tends to find a way, by whatever means necessary to express itself. (Again, this is something artists have observed and talked about for centuries, but I can't prove it to you.) And if the impulse keeps up, ambition seems to follow, and attention is sought, educators put in their two cents, peers give compliments, a larger community of artists is sought out, etc. Or the artist become a monomanical autodidact (Stanislav Szukalski, for instance) and attempts to train themselves. So generally if you are looking at anybody's work over the age of 27 or so, you can assume that they have made it through the crucible of the "get a real job" era of life with their creative impulse intact and they have some degree of dedication, have pursued their craft in some way, and probably have been at it for over a decade.
You then look at the work, and if there isn't something to it that one might call hypnotic or magnetic or full of some eerie or strangely powerful quality of life that you can't quite put your finger on... then you aren't seeing the product of a highly talented person. You may appreciate the polish of it, how finished it is, how much it looks like a photograph, how clean and bright the colors are, or how simple the design or something, but you won't feel it in the sense that I mean.
Now, I wouldn't say that it takes talent to experience this quality in a work of art. I think it does take talent to distinguish that quality from craft in any particular artwork. People who are highly intellectual but not talented always look at the wrong subtleties in art. People who are highly talented and accomplished are much more sensitive to real artistry, the hints and suggestions that only talent can provide a picture through vital instinct. (Can't prove any of this, just know it through long experience.)"