I forget where I read it, but I'm pretty sure that at some point there were millions of elves on Middle-earth, and by the end of the third age, it's down to a few thousand, aka a very small portion. These are the elves that got told way back in the first age, "Hey, just so you guys know, you're totally welcome to come back and live in heaven now without any worries" and responded, "No thanks, we're good!" and then proceeded to not only hold to that but survived the next 7.000 years of bullshit including but not limited to:

Multiple continents sinking into the sea

orcs

dragons

balrogs

multiple wars with Sauron, a literal divine being

The rise and fall of several human empires

more orcs

wargs

a bunch of their territory being overtaken and burned to the ground

And all of their loved ones either dying or sailing, even though we know that grief can and will kill an elf

Like, you can't tell me that third age elves start showing up in the undying lands, where everyone has spent the last few thousand years basking in the magical equivilant of free therapy and probably have as many defence measures as a suburban coldesac, and aren't viewed as the most feral, twitchy, paranoid mother fuckers; held together by suspicion, stubornness, and at least 25 contingencies for every situation they've collectively encountered during their time in Middle-earth.

My favorite examples of feral, hyper-vigilant behavior include:

Elrond: Security clearance; sure, Turgon may have threatened to kill anyone who tried to leave his hidden city, but he also took an entire army out of and back to the city at once, and then also didn't realize that his own nephew snitched on where the city was. His security protocols sucked. Meanwhile, Elrond had hundreds of strangers coming in and out of Rivendell for over 3,000 years, at one point completely surrounded by enemies and full of nothing but a bunch of refugees, and Sauron still never found it. You can't tell me that he didn't have at least 25 security checkpoints on the way into his city(sorry, house-that means it's private property, right?), even if you didn't know they were there.

Galadriel: Paranoia; This woman was magically keeping track of everyone she knew and even did it often enought that she knew what to look for of those she couldn't directly track (gandalf) and looking into their minds and testing them. All while having Sauron constantly clawing at the walls of her mind, at least for a few years

Thranduil: Spite; it was basically only his sheer audacity holding his nuclear bunker- cough cough- sorry, I meant vast underground halls together, while his next-door neighbor was some cursed ruins, a dragon-infested dwarf kingdom, and evil, man-eating, car-sized spiders on his front lawn.

Haldir: he blindfolded the fellowship when they tried to enter his city (super secret hideout), need I say more?

Multiple examples of groups of elves jumping out of trees fully armed and ambushing anyone who wanders into their territory. And while the characters seem surprised to be ambushed, they don't seem surprised that elves ambush people in general, leading me to believe this is normal behavior.

Elrond: does it-

the second era gang

they are only there some of the time or at certain entrances (possible but prosaic, includes the potential for tra la la lallying as shift work)

elrond’s magic has some kind of built-in warning system and they cleared out to avoid potential danger (plausible and realistic considering that i don’t think team tra la la lally is either interested in fighting or skilled in emergency response)

the changing political climate and increased danger around rivendell resulted in all tra la la lallying activities being moved inside the valley (which begs the question of where, and if they just manifest barbershop quartet style beneath guests’ windows)

elrond didn’t know about it until bilbo unwittingly mentioned the experience over dinner, and all roadside tra la la lallying was brought to an end (either petering out without the allure of secrecy or simply by the power of elrond’s consternation)

the whole thing was contrived solely to troll the dwarves (elucidates the standout conformity of only these elves to historic ‘tree-dwelling hippies’ stereotypes)

bilbo fully made it up (this was revealed when merry and pippin cheerfully asked elrond when the tra la la lallying would start, and elrond said ‘gesundheit’)