SAN FRANCISCO — In Europe and the United States, the conventional wisdom is that regulation is needed to force Silicon Valley’s digital giants to respect people’s online privacy.

But new rules may instead serve to strengthen Facebook’s and Google’s hegemony and extend their lead on the internet.

That could begin playing out next month, when Europe enacts sweeping new regulations that prioritize people’s data privacy. The new laws, which require tech companies to ask for users’ consent for their data, are likely to hand Google and Facebook an advantage. That’s because wary consumers are more prone to trust recognized names with their information than unfamiliar newcomers. And the laws may deter start-ups that do not have the resources to comply with the rules from competing with the big companies.

In recent years, other regulatory attempts at strengthening online privacy rules have also had little effect at chipping away at the power of the largest tech companies, ultimately aiding internet giants rather than hurting them.