The assessment is based on the strong primary evidence presented in the most authoritative and relevant source. The Fierce Healthcare article, a reputable industry publication, provides a concrete data point of a major insurer (UnitedHealth Group) earning $2.3 billion in a single quarter. This is a direct and unambiguous example of a significant 'financial gain.' While this source also mentions challenges like 'medical costs' and 'regulatory pressures,' these factors do not contradict the ultimate outcome of profitability. Experiencing financial gains means that revenues exceeded costs, even if those costs were high. The political commentary from Jacobin, despite its low authority and clear viewpoint, corroborates the core claim that insurance companies have been profitable under the ACA. The other sources are not useful for this assessment: the HCA Healthcare link is irrelevant as it concerns a hospital operator, not an insurer, and the Facebook post is a social media link with negligible authority. There is no direct evidence among the provided sources to contradict the claim of financial gains. Therefore, with a high-authority source providing specific financial data showing profitability, the statement is very likely true.