For long-term wealth building, there's no meaningful contest. But the right answer depends on your timeline and what the money is for. Here's the honest comparison.
A high-yield savings account earns 4–5% in 2026 (and will likely earn less when rates fall). A global equity index fund has returned roughly 7% annually after inflation over long periods — meaning 9–10% nominal.
On $100,000 over 20 years: savings account at 3% average = $180,611. Index fund at 7% = $386,968. The index fund produces more than double the wealth from the same starting point.
The rule of thumb: if the money has a timeline over 5 years, invest it in a low-cost global index fund. Anything under 3–5 years, keep it in savings. The volatility risk of index funds is a fair trade for long-term growth — but only when you have time to ride out downturns.