We have both been "savers" all our lives. We love yard sales, thrift stores and growing our own food. I wouldn’t say we lived a spartan life but we didn’t have a huge house and fancy expensive cars. If we wanted something that cost a bit more we would save up for it and not charge it to get it now. By being careful with our income we managed to take an early retirement (53/55) and can take a big trip every couple of years.

being debt-free in general has nothing to do with investments.
to stay out of the debt, spend less than you earn. very simple.

if you have a lot of debt – you should be paying that off before you start trying to invest anything – the interest rate you pay on credit cards is a lot higher than any interest income you would get from investments over time, so you get a lot bigger return for your money by paying down debt on 19% credit cards, vs investing it in a bank cd at 1-2% or hoping for 10% return over the long term with stocks or mutual funds

my only debt is real estate related (3 houses + a land loan) or car loans (only $242/month pmt) and I have $40,000+ in my 401k plan – it’s taken 6+ yrs to get to that point, but now it’s gotten to the level where it starts growing faster, plus I’m increasing my contribution % every year and I get more than 50% of my first 6% in company match (free money!) – I full expect to have $500,000 in there when I retire (early) in 2023