Different people will have a different of opinion on this. As full disclosure, I am NOT a fan of 50/50 splits in general and have had my fair share of businesses and startups.
Here is my take:
1. Your first bullet point is irrelevant. You not having a job doesn't mean you couldn't get a job to lower risk if thats the way you think (although thats not a good way to think at all). Him having a job doesn't mean much. What matters is what you each bring to the table and what you contribute. If your argument was more base on time commitment rather than risk, I'd agree.
2. I HIGHLY disagree with this argument. A lot of HN love to downplay the non-technical founder (with good reasons) but a valuable non-technical founder who have the skills (which many who start out don't) is worth their weight in gold as well. The non-technical argument here is more of a bias use case than a fair assessment of what each is bringing to the table and how that will contribute towards the startup.
3. This one is valid. As someone else noted, check for liabilities regarding this. The fact that you are going to be putting in more time makes it somewhat valid that the split should not be 50/50 starting out. Unless he is investing some money and willing to put in equal time, among other things, it would be very difficult to justify a 50/50 partnership. That said, if you value and trust him, and he does bring the goods as you say (not just perceived), then you will need to figure out fair compensation otherwise.
TL;DR 50/50 probably doesn't make sense in this case but some of the arguments presented are invalid in my personal opinion.
Equity splits have at least as much to do with risk as they do with contribution. But it's risk in a more general sense; you don't get compensated for being so financially insecure that the venture might wipe you out completely. Instead, it's "risk" that captures opportunity cost.
Unfortunately for the poster, despite the fact that his prospective partner already has a well-paying job, his risk in starting this company could be higher, because the opportunity cost to an established CEO of joining on with an unproven venture is very high. CEO's tend to "trade up" to other CEO roles at established companies.
I think doing a startup is risky for a lot of people in general. Comparing risk in the manner the OP did is poor. I think to succeed you have to have a certain level of risk tolerance. There are a lot more things to consider and compare than who risks more financially or in opportunity cost. Getting into a startup requires more commitment than that in my personal opinion.
Now if you're talking about risk appetite in doing things and jumping into a startup, then I'd agree risk is a factor worth taking note of.
"Contribution" can actually be measured in terms of risk; the risk is the opportunity cost of the value of that contribution to any other business you had the option to be a part of.
Risk is more important than your writing seems to indicate. Equity isn't an achievement award.
I think you read my comment wrong then. I never undervalued risk in any way. I agree its one of the most important factors. But I think the type of risk is more important than what you lose out on as opposed to the other guy.
Here is my take:
1. Your first bullet point is irrelevant. You not having a job doesn't mean you couldn't get a job to lower risk if thats the way you think (although thats not a good way to think at all). Him having a job doesn't mean much. What matters is what you each bring to the table and what you contribute. If your argument was more base on time commitment rather than risk, I'd agree.
2. I HIGHLY disagree with this argument. A lot of HN love to downplay the non-technical founder (with good reasons) but a valuable non-technical founder who have the skills (which many who start out don't) is worth their weight in gold as well. The non-technical argument here is more of a bias use case than a fair assessment of what each is bringing to the table and how that will contribute towards the startup.
3. This one is valid. As someone else noted, check for liabilities regarding this. The fact that you are going to be putting in more time makes it somewhat valid that the split should not be 50/50 starting out. Unless he is investing some money and willing to put in equal time, among other things, it would be very difficult to justify a 50/50 partnership. That said, if you value and trust him, and he does bring the goods as you say (not just perceived), then you will need to figure out fair compensation otherwise.
TL;DR 50/50 probably doesn't make sense in this case but some of the arguments presented are invalid in my personal opinion.