For me I think ones level of success depends on a number of factors.
Personality: I think physical attraction catches the eye but it is ones personality that will hold there attention. If one has an undesirable personality or lack of personality no matter what looks or money or other factors they possess in the end it will become in vain because the other will eventually tire and move on.
Geographical location: I think many people deep down would prefer to meet somebody within a certain distance and not have the inconvenience of traveling back and forth for a relationship, so success depends on the number of people within this desired area. Geographical location is less relevant to those who want to date but for those seeking something more longterm it does become an issue.
Freedom to move: Most people have roots let it be career, family or other commitments and for many to start over again in a new environment, it is not the most pleasant issue to contemplate and sometimes not possible and notwithstanding the fact that the person would have to be extraordinary in the first place to even contemplate this, as they would say from a marketing prospective they would need to resemble a monopoly where there was no substitute product.
Never give up: For those who indeed find success from internet dating, this seems to be the most common piece of advise. For me this is a poison chalice, we are human and we often read into things. If a person informed you they had been a member of a site for e.g 5 years, it is unlikely too many would see this as a great commitment on there behalf to find love rather people could potentially see this in many other less positive ways.
I would love to hear other people's views of what determines success through internet dating.
I would agree with you on all four points, and add these points -
Honesty - if your profile says you live in MyTown, and then in emails or chatting you say you live in ThatTown, you are not being honest in your profile. I then I run away from you. No honesty up front, no point in even getting started.
Pic(s) on the profile better match what I see when you on the webcam. Oh yeah, if you can't show yourself on a webcam, goodbye. And saying you don't have one is no excuse, there are internet cafes everywhere, libraries, colleges. There's no excuse for not showing yourself on a webcam these days.
If your profile says Long Term Relationship/Marriage you better mean it. That is entirely different from FWB. Again, that is part of the Honesty bit above, but I've come across that myself, and it turned out to be a big disappointment when she couldn't decide what she wanted, other than to come over for sex. (sorry for my personal rant)
Be prepared to meet and greet many, many people. You can't just wait for one person to come and sweep you off your feet and live happily ever after. You have to get out and meet many people, otherwise you won't know who is the right one. Too many women I've talked to just want to sit and wait for the one guy, passing by guys they might like, and worse yet, maybe missing the one guy they are looking for because his profile pic isn't the best. I'm not talking about being a 'player', that's a whole different ballgame.