Basically it’s the investment and the amount of that investment that makes the money not the wrapper that investment is in. e.g. a pension is a wrapper, so is an ISA.
Your colleagues mention not having money tied up, so they are realistically investing in an ISA with no tax relief or employer contribution. Big mistake.
You mention a “pot” with a value so you are talking about a DC pension.
Let’s take a DC pension, it might be invested in FundXYZ. You could also buy FundXYZ in an ISA. So if your employer gives you free money into your pension on top of the tax-relief that then it makes far more sense to buy it in your pension. i.e. £100 from you plus £100 from your employer plus £50 tax relief that grows by 100% in the next 15 years would give you £500 ending value.
If however, you think the options for investing in your company pension are all pretty rubbish options then putting £100 into an ISA with no employer contribution or tax relief buying FundABC or CompanyX shares instead, would need the investment to grow by 500% to match that £500 ending value.
It could well be that your younger colleagues want access to the money in case of emergencies (and that points ot them being financially illiterate - they should have an emergency cash savings buffer for this in case of loss of job - and so should you). The price they are paying for this is massive.
Your younger colleagues should be investing in the company pension and because they are young should be investing in the highest risk category fund(s), or even better 100% in the stock market as a low cost index tracker if that is an option in the company pension.