The only tournaments that automatically convey the GM title are major international events like the World Junior Championship. This tournament has been won in the past by the likes of Spassky, Karpov, Kasparov and Anand. To suggest a 1300 player is going to win such an event is silly.
I do not what the true odds would have been, but back in the mid-70s a bright star named Charles Daniel entered a big money tournament in Atlanta for those rated under 2200, with a grand for first (that would be about ten times more in today’s hyperinflated greenbacks). Charles was unrated, having never played in a rated event. I seem to recall Charles winning the tournament with the only blemish a draw. In addition, his last round opponent, who became a NM, as did many of those playing in the event, played a Winawer French. There should be details of this tournament somewhere. Seems his opponent was a half-point ahead going into that last round…
Charles and I became friends. We studied chess, while also playing many fifteen minute games. Charles learned chess while playing many games and matches (think La Bourdonnais – McDonnell) with a school friend before entering the tournament.
I see no reason why some player much younger than Charles, who was a teen, could not enter a tournament or two, obtain a 1300 rating, spend several years training and studying, as did Charles, and not return to tournament chess competing well enough to play at a GM level, keeping in mind that what is required to become a GM these days is vastly different from what it takes to actually play like a GM. For example, consider this, from Chessbase:
South Africa’s first Grandmaster
by Priyadarshan Banjan
1/4/2015 – With an Elo-rating of 2399 (January 2015) Kenny Solomon is South Africa’s number three but a few days ago he became the country’s first grandmaster. In the Africa Chess Championship 2014 he finished with 7.0/9 and had a better tie-break than tournament favorite GM Ahmed Adly, World Junior Champion from 2007. This tie-break win made Solomon Grandmaster.
en.chessbase.com/post/south-afri … randmaster
Contrast this with GM Magnus Carlsen, rated 2844, a difference of 445 rating points, yet they both hold the GM title.
In regard to the comment by Randy, " Probably the most surprising result was an Expert once winning the World Open (although even then that was not nearly the tournament it is now). I think he beat a couple GMs/IMs and probably drew with a couple more. Still, a really strong result," this is at the now discredited Wikipedia website:
“Alan N. Trefler (born March 10, 1956) is an American businessman, who is the founder and CEO of Pegasystems. Trefler also serves as chairman of the company’s Board of Directors.[4]”
en.wikipedia.org/wiki/Alan_Trefler#cite_note-11
Also at Wiki, via “[11]Chess Life & Review, September 1975, pp. 586-87,” is:
“While at Dartmouth, Trefler entered the 1975 World Open Chess Championship in New York. He entered the tournament with a 2075 Elo rating, 125 points below the lowest master-rated player, ranking him 115th overall in the tournament. He went on to be crowned co-champion along with International Grandmaster Pal Benko, who was rated at 2504, and placed ahead of Grandmasters such as Walter Browne and Nicolas Rossolimo, and future Grandmaster Michael Rohde.[11]”
As for the comment, "…the World Open (although even then that was not nearly the tournament it is now)…I would like to comment that NO tournament then was nearly the tournament it is now. Even with natural rating inflation there are simply vastly more higher rated players now, which may make it much more difficult today for any player having a “career” event in any tournament, anywhere, at anytime.
This is reminding me of Rosendo Balinas. Need to do a little research, though, before I post about that.
In order to win a tournament that directly awards a title one must actually play in that event. None of them are open events. Even a player who did all of the wonderful things Jion_Wansu suggests are possible, he or she would not magically be allowed to play in one of these events.