Problems with the government's main health care overhaul website carry a bigger risk than frequent crashes: Higher prices could follow for many Americans if technical troubles scare off young people. The government has touted recent improvements to HealthCare.gov, which millions of Americans are expected to use to sign up for coverage. But enrollment still lags far behind projections, and that has triggered worries that legions of potential customers in their 20s and 30s might not sign up. If that happens — and older, sicker people continue to register in larger numbers — insurers might have to raise future prices to address the imbalance.