Luck is random, but not uncontrollable. Successful people manufacture their own luck: live in the place where things happen, go to places where right people hang out, make yourself known and useful to well-connected people, attack the market where chances are tilted in your favor, be approachable, partner with people different from you so as to maximize your "luck surface area", the list goes on and on.
All the things you described can also increase your bad-luck surface area. You are confusing bad-luck with inaction, which is not the same. You might end-up meeting wrong people, work on wrong ideas, hire wrong people, get wrong publicity, wrong timing etc etc.
I would say "partly" rather than "largely". I think the reason luck seems to be such a significant factor is that everything else that depends on your idea, execution, networking, and so on are all tough, and exceptionally so en masse.
So, to minimise the impact of luck, you'd need to hit home runs in every other aspect which is unlikely. If your idea is great, but the rest so-so, then luck might seem like a stronger factor, and that's the sort of situation most of us would be in.
I beg to differ. Take the best 10 people, which are all the most dedicated, hardest working, most compentent: If these compete on the same idea in the same field, only one of them can succeed.
After all, running a startup means taking risks, and risks are just another word for stuff that you don't have under control, and which is best described by probability.
In which case, luck is still partly a factor rather than largely a factor. It's only accentuated in that case because your hypothetical has every venture pushing each facet to the limit.
More realistic would be 10 ventures where a couple bail, another couple just don't have a professional network, another has a great network but an ugly design or awkward name, and so on.
Even if you follow all of the above, there is a 90% probability you will still fail. Startup success is still largely dictated by luck.