Did i say he's the greatest, or that there aren't more experienced people out there? I didn't say anything about these things so why are you randomly throwing in these assumptions? If he would've started this project with someone else then sure, i'd agree, but bringing someone else in halfway through isn't that great. Not when it comes to creative work and not if you don't like working with others. He has people for proofreading and playtesting from what i know and that's enough.
I took a glance at the patreon and he doesn't have a dollar goal tracker to show his total monthly pledges. With 7500 patrons he's probably doing pretty well, but generally the average $ per patron for Patreon creators is a lot lower than you'd think: You have some superdonors, but a huge porportion of your pledges are for the minimum. I doubt he's averaging even $5 per patron; that would mean he's taking about 40k/month, which is obviously enough to hire people but is far from 'enough money to start a game studio' or whatever people were saying above. Hiring employees is expensive, as if you want stable staff you have a lot more expenses than just salary rates (payroll taxes, benefits costs, etc): actual salary is usually only around 60% of what the employer spends per employee, give or take a bit (benefits are more expensive for small businesses than for major corps, as they lack purchasing power leverage. Also, in tech industries you generally wouldn't expect real employees to do all their work on their personal computers, which may not have the capability to do what you want, or the software - you'd want to be using standard technology, same IDE, etc for your work. If you don't do that stuff, you have massive turnover and you never really recoup your cost per employee, as employees don't generally generate value for the employer until they've been working for a bit due to the overhead costs of hiring and training.
I would guess that DPC has the ability to pay for a few full time employees, and its possible testers, script proofreaders or writing assistants, etc are more valuable to his work than additional programmers. It's also possible it'd just be a very good idea for him to bring in a secondary programmer with the understanding that they wouldn't be working on the things he's most concerned about - just having someone who cleans up bugs, streamlines code, fills in dialogue from the scripts, etc would probably be pretty valuable. It's also possible he already has all of those things in place, and they're not what cause production bottleneck in the first place.
Adding additional help is much, much more complex than people tend to portray it as, and the way people talk about it usually tells you if they have any experience in a hiring/firing supervisory role in any business.
Another consideration are non-employee business costs, from hardware upgrades to licensing. When you're in full for-profit, professional, putting your game on Steam mode, you start to incur software licensing costs for the products you use to create your game, especially if you want to add employees (because you don't hire people and expect them to buy all their own software, and you really need everyone to work on the same platforms). In particular, this game licenses music. That costs money! I'm not sure I really believe that is a good use of resources, but, then again, I play most of these kinds of games with the volume off anyway, so ... I'm the wrong person to ask about that. But it's definitely a cost, and it might be more than you think because I wouldn't be surprised if some artists are surcharging higher for an XXX product than they would a more mainstream one - that's pretty common (and another reason why it seems like licensing so much music is unnecessary, but I guess for people who play with music having appropriate music in all the party scenes and things is probably a good thing)