How does that happen? I mean, the world is geared for survival of 1st level. At first glance, that means that, say, 4th level and up are pretty much a cakewalk. Maybe a slow cakewalk, but a cakewalk, regardless. How does this end in a feeling of achievement?
"Geared for potential survival" =/= "Will survive".

In my Pathfinder Beginner Box game recently, the most experienced PC, Kyra, was 3rd level, nearly 4th, when she bled out to a goblin arrow. The two 3rd level PCs had been ambushed by two regular goblins with shortbows, and got very unlucky - I don't use critical hit confirmation roll, Kyra took a crit between the shoulderblades and her companion Cam had no healing ability or potions. It was the second dead PC that day; the 10d4 damage (save twice for half) gas trap in the Dark Chateau had already done for their 2nd level companion. Motto: Don't bash Zagyg's spellbook chest.

There are areas of greater and lesser danger in the world. There are many areas suitable for 1st level adventuring, and rare areas that will test high level PCs. There are trolls in the marsh, you've probably heard of them, but you probably want to be at least 6th level before you go take them on. There's a dragon up on Serpent Ridge. Maybe you can take Black Fang at 1st level - maybe not.