The interest rate on mortages is always higher compared to the interest rate on leverage for stock (by using the stock itself as collateral).
You can get close to the yield on swiss confederation bonds if you buy well priced, leveraged ETFs.
Obviously that interest rate is as stable if not more stable than the interest rates on mortages.
Please DO NOT buy stocks with money from a mortage. you're just giving up at least 1% yield.
Please note that with leverage (stocks or real estate) is is possible to lose more money than you invest.
https://www.quora.com/How-does-a-land-value-tax-not-create-d...
Switzerland is not very home ownership friendly, at least there are very little tax incentives for it (personally I'd rather have people invest their wealth into productive things rather than real estate, so I find it good). In large cities most places are owned by banks/insurances/other real estate companies and rented out.
[1] https://www.swissinfo.ch/eng/wealth-ranking_swiss-are-world-...