Is this like "have the hackathon participants do manual neural architecture search and train with L1 loss"?

Ah, I misinterpreted your question. I thought you were looking for ideas for your team that was participating in the hackation, not as the organizer of the hackation. 

In my experience, most hackathons are judged qualitatively, so I wouldn't worry about ideas (mine or others') without a strong metric 

>75% confidence: No consistent strong play in simple game of imperfect information (e.g. battleship) for which it has not been specifically trained.

>50% confidence: No consistent "correct" play in a simple game of imperfect information (e.g. battleship) for which it has not been specifically train. Correct here means making only valid moves, and no useless moves. For example, in battleship a useless move would be attacking the same grid coordinate twice.

>60% confidence: Bad long-term sequence memory, particularly when combined with non-memorization tasks. For example, suppose A=1, B=2, etc. What is the sum of the characters in a given page of text (~500 words)?

Above 99% certainty: 

Run inference in reasonable latency (e.g. < 1 second for text completion) on a typical home gaming computer (i.e. one with a single high-powered GPU). 

Didn't this basically happen with LTCM? They had losses of $4B on $5B in assets and a borrow of $120B. The US government had to force coordination of the major banks to avoid blowing up the financial markets, but meltdown was avoided.

Edit: Don't pyramid schemes do this all the time, unintentionally? Like, Madoff basically did this and then suddenly (unintentionally) defaulted. 

But if I had to use the billion dollars on evil AI specifically, I'd use the billion dollars to start an AI-powered hedge fund and then deliberately engineer a global liquidity crisis.

How exactly would you do this? Lots of places market "AI powered" hedge funds, but (as someone in the finance industry) I haven't heard much about AI beyond things like regularized regression actually giving significant benefit.

Even if you eventually grew your assets to $10B, how would you engineer a global liquidity crisis?

+1, CLion is vastly superior to VsCode or emacs/vi for capabilities and ease of setup, particularly for C++ and Rust

It seems like this is a single building version of a gated community / suburb? In "idealized" America (where by idealized I mean somewhat affluent, morally homogeneous within the neighborhood, reasonably safe, etc), all the stuff you're describing already happens. Transportation for kids is provided by carpools or by the school, kids wander from house to house for meals and play, etc. Families get referrals for help (housekeeping, etc) from other families, or because there are a limited number of service providers in the area. In general, these aren't the hard things about having kids. 

In my experience, here are the hard things:

• The early months / years are miserable. The kid wakes you up in the middle of the night and won't go back to sleep and you don't know why. You're in a constant state of sleep deprivation. This happened to me even though I had a night nanny for the first few months (which was hugely helpful, but did not completely eliminate the problem). I got off easier than my friends who had such a problem that they finally hired a "sleep coach" (yes this is a thing).
• Your kid is sick, and you need to take care of them. You could outsource this if you had live-in help, but in practice there is a biological imperative to make you want to do the caretaking yourself.
• Your kid has physical or mental issues. This doesn't necessarily mean anything like they're in a wheelchair or have severe learning disabilities, it could mean something like attention issues or delayed fine motor skills.
• The kid needs almost constant supervision, particularly in the early years. Again you can outsource this to a limited extent (e.g., with daycare) but as a parent you want to spend some time with them (because if not, why have the kid at all?)
• Even when things are going smoothly, there are significant coordination costs. Do you and your partner both need to stay late at work? Figure out who's going to pick up the child from school (and make sure the school has all the appropriate forms allowing that person to pick up), arrange childcare for the night (will you be home early enough to put your kid to bed?), etc.
• You finally got home and you're dead tired. Unfortunately at 3am your kid wakes you up because they had a bad dream. This happens more than once per week, for various reasons. 
• There's a trade-off between living in the best place for your work and living in the best place for your kid. Would it be better for you to live in the heart of Manhattan (or wherever) for your job and career socializing? Probably yes. Is it the best place to raise kids? Probably no. 
• You can never again give 110%. You know those couple of weeks you had crunch period and had to work 80 hours? You can't do that anymore. No one else can actually replace you as a parent for your own kid. Or rather you can, but you have to be aware that you're now actively putting on the trade of "sell relationship with child."