It's the other way around really, the value of the crypto dictates how much money you can spend mining it and still break even. Except then the difficulty will increase and even things out. Having more miners could increase the trust in the currency and increase its value but it's not directly correlated.

Mining from a random browser will almost certainly never be cost effective for the user, you're better off buying or renting dedicated hardware, mine on it and use the reward to pay for microtransactions.