Cash out refi on primary for DP on investment property

[Christian Weber]

Firstly hello - long time reader and first time poster 

Some advice needed

I have 155k (24 yrs) left on Primary mortgage at 4.1% (home worth 320-350k)

If I cash out refi I potentially can take up to 100k out / drop interest rate to high 2's/vry low 3's and have a payment $200 up on my current monthly

I will make around 160-200k USD this year from my jobs (more if I buy a rental) and my mortgage is within $100 a month paid off by roommates (I cover the utilities which are $300USD a month)

Question is with money being really cheap would it make sense to cash out 100k to have it and either stick it in the s&P500 or use it for DP on 2 or 3 investment properties?

I was considering doing a heloc and using it to flip some houses but my business partner went potty and cant rely on him anymore. I currently have about 60k in an emergency fund as well

All input appreciated

I also dont mind holding until this eviction thing passes and some homes might hit the market in sept/octo however it takes a month to cash out refi