B) your reasons are just not buyable for some of us, clearly. Comparing to Spain and Columbus doesn't make any sense at all - Columbus knew the earth was round, knew that if you went west far enough you'd hit the Far East and the lucrative trade routes there. It wasn't a one way journey into the unknown, he did it because he wanted to become rich.
That wasn't my only reasoning. You skipped over all the rest of my reasoning last time around, and changed subject to your "my only problem is population" thing, which is noticeably absent from this post.
And again, I keep having to repeat this very simple fact: When you're talking numbers in the billions, statistical probability rears its head. If you can't conceive of the notion that a fraction of a fraction of a fraction of a percentage of a population might be interested in other things than monetary gain, then I mean... what's the issue really?
C) Technology wise, up until the andromeda initiative is revealed there's absolutely no indication that any species has the capability to do trans galactic flight. So now we aren't just going from a situation where after 27 years humanity is a galactic superpower, we're in a scenario where after 21 years since first meeting alien life humanity hasn't just developed new tech none of the races whove been around for hundreds of years have, but also it's able to persuade these species to join up on this crazy, lunatic endevour.
As I've said before, it's
improbable, but not
implausible. Like most things that happen in the Mass Effect universe, if not all science fiction. (ever seen the list of inconsistencies in Star Trek?) What are the odds that we could actually defeat an ancient alien race that has been evolving for literal eons? Very low, I would say. But if we don't, you don't have a story. Same goes for the exact timing of the reaper attacks. What are the odds that the reapers attack a couple of decades after humanity join the galactic civilization when the asari have been around for 2000 years?
And by the way, given exponential technological advancement (let alone magical space artifact that jumps our technological level ahead by 200 years), this is absolutely possible. Remember, in 1914, France was still doing cavalry charges. By 1948, we'd be dropping atomic bombs from planes. And let me reiterate, that's without a magical knowledge imparting monolith.
Improbable? Sure. Not implausible.
D) resources are important. Mass Effect isn't post scarcity. Wars are still fought over planets, colonies still cost the earth yet look like trash. The Andromeda Iniative is basically building a new citedall, plus four ark ships, and all of them can sustain a 600 year galactic flight. This isn't Elon Musk funding a rocket that might go to the moon one day, this is him finding a faster than light space ship. Next year.
Hell, look at the resources that were needed just to construct the crucible. The andromeda iniative is far larger in scope, and yet somehow no only did no-one notice it, but it was done by private funding? From a species that didn't even known alien life existed 21 years ago?
The crucible was built over a span of 1-2
months.
This is its size. It was also built in secret, so they hardly had the resources of all species combined.
Also, they aren't building a new citadel. They've said it's based on its technology, but it's very clearly much smaller. For example, the citadel's population is 13 million, while the total number of people going on the AI is clearly well under half a million. Which, in terms of pure size,
puts it well under what the crucible is compared to the citadel. And remember, the crucible was something they only just found out about too. You really can't conceive of them building something far smaller in scope than the crucible in like 30-40 times the amount of time?
My guess would be that there was some "hidden tech" in the mars beacon, and that the technology needed for trans-galactic travel is based on that. We know it's possible for species to hold back information imparted by those beacons, seeing as how the Asari have done the same in the original trilogy.