Since when is 20 years from now "soon"? On the other hand, if there are space pirates out there Apophis is just right to use for blackmail. "Nice planet ya got there, be too bad if anything happened to it!". Although there is the question of what we have that they they would want.

Not exactly true that we have never built self-sustaining ecosystems -- if you mean an enclosed environment that can produce its own air. Submarines have been able to do this for a very long time. Just add water and electricity.

Sending those in their 60's is a great idea. Here is why. (1) They're going to die anyway. (2) No medicare/social security/etc. costs (3) In a low gravity environment they should last longer (and if not, see #1) (4) They can slowly build out the infrastructure of the colony. (5) We know they are "done" when they can build a ship that can return to Earth orbit which can transport at least, oh say, four passengers back to Earth. Alive.
At that point, the colony will be self sustaining. Only then do we send fertile people that can produce and raise children.

It has been said that "Extraordinary claims require extraordinary evidence" (Sagan) or that "Extraordinary claims require extraordinary proof" (Truzzi). However, is not the assertion that something -- anything -- is extraordinary itself an "arbitrary claim"? After all, the claim is normally made to dismiss something else as extraordinary. But what is the basis of the claim itself claiming something else is extraordinary? The problem is that the history of science is littered with broken paradigms that asserted what whatever replaced the paradigm was "extraordinary" and therefore could be ignored.
I give a single example. Medicine ignored the concept that stomach ulcers could be caused by bacteria because "of course" bacteria could not survive in such a hostile environment as stomach acid. In this case orthodox medicine claimed that only "extraordinary evidence" could satisfy the assertion that ulcers were caused by bacteria. In point of fact, the evidence was not particularly extraordinary -- it was proven that Helicobacter pylori was the main cause by swallowing it, getting ulcers, then using antibiotics to kill the Helicobacter pylori. And since people with ulcers were very motivated to find a resolution, a cure for most stomach ulcers was distributed and a Nobel prize in Medicine was awarded.
I suggest that the assertion that something is "extraordinary" and therefore requires extraordinary evidence (or proof) is itself an arbitrary claim and should not be regarded. And that we should use the same standards of proof or evidence for everything.

When you work it all the way down, most code issues are about the money. Companies sell code to make money. They want to pay as little as possible to produce it. And make as much as possible from it. Bad coders, ignorant coders, lack of testers, bad testers, ignorant managers, lack of processes -- all of it. Bad coders have jobs because companies only want to pay so little that only bad coders take the money. Ignorant coders of course are paid little. Testers cost money -- so hire as few as possible or have the bad ignorant coders test their own code. Hire/keep potted plants as managers because they are cheap. Take the money and run. Ultimately this is the root cause of it all. And it will never change. This is the way it was 30 years ago. This is the way it is today. This is the way it will be 30 years from now.