A 31-year-old millionaire who has 7 different types of investment accounts says that his HSA is 'my favorite by far' — and explains how he's using it to build long-term wealth

• Brennan Schlagbaum and his wife paid off six-figures in debt and now have a net worth of nearly $2 million. 
• The couple invests in index funds across various investment accounts, from IRAs to a brokerage account.
• Of all of his different types of accounts, his favorite is his health savings account (HSA).

Brennan Schlagbaum has a simple approach to investing — he puts most of his money in three index funds — but he does have a lot of accounts to juggle.