Savings vs paying off as quickly as possible

Has anyone considered saving the money into a brokerage that they would ordinarily pay towards student loans? I keep crunching the numbers and even if I didn’t pay the monthly interest accrued on my loans, and instead invested the monthly $3500 payment I would normally throw at my student loans, I’m still strangely coming ahead by $10,000, assuming a 4% return on investments. I use a pretty handy spreadsheet to calculate interest accrued, payments, and payoff dates via the Vertex42 debt calculator. The liquidity gives me more comfort knowing I have a nest egg if I lose my job, but after two years there would be plenty of money to pay off my student loans in full. A brokerage is after tax money so I can pull out the original amount without penalty. Has any else done this? I’m on PSLF as well and have about 6 more years, but don’t really want to stay teaching for 6 more years when my loans could be done in 24 months. Also, I’m on SAVE forbearance rn. Haven’t heard from my service provider yet about recertifying or being moved to a new plan yet, so kinda banking Inslip through the cracks? I’m second guessing throwing all this money at my loans when the economy is not doing great and I don’t want to throw all this money at my loans over the next 2 years with nothing left in savings should shit hit the fan. Trying to figure out the math game over here to come out ahead with some extra monetary stability. To give y’all an idea, I have about 60k in federal loans with an average 6% rate.