Recently, high-deductible health plans (HDHPs) have become more common in private health insurance markets. The 2021 KFF Employer Health Benefits Survey finds that 66% of firms with 1,000+ workers offered a HDHP in 2021, compared to 32% in 2010 (report here; https://www.kff.org/report-section/ehbs-2021-section-8-high-deductible-health-plans-withsavings-option/). Using economic theory, discuss the relative merits or down-sides of these types of plans from the perspective of insurers and/or enrollees.