Everything is Unique, Nothing is Unique
There's an aphorism that says if you can make it, somebody else can fake it.
Fakes will always be identifiable, given the right knowledge, tools and impetus to actually investigate. The third component is often the most vital: the suspicion of nefarious activity - and the absence of this is where most fakes succeed. You accept a banknote in change from a supermarket purchase and probably put it in your purse/wallet/pocket without looking at it - you might subconsciously check it's the right colour for the denomination but not notice it's a £5 from the Bank of Egnland. Most of us will, at some time, have started to pay for something, only to notice we're handing over a foreign coin (the £1 and 1€ coins are easily mixed up, for example).
So it is online. A healthy dose of cynicism regarding special offers is vital; if it looks too good to be true, it more often is. Yes, popup and ad blockers are useful, as are AV tools, but they should be treated as the backstop, and only partly effective ones at that.
Since the C-19 lockdown started, and it was clear it was going to be more than a few weeks, I've been introducing computers and tablets to a number of elderly people in my area. Some have a suitable device in their home (provided by a relative); for most others, I'm handing over their first contact with such tech. Most already have a healthy dose of suspicion with anything online so it's a balance between giving them the courage (and skills) to try something new and being cautious. They don't know what to expect, so won't recognise when something is different and should be avoided. The general rule I give is that if you didn't ask for something, be suspicious and, if in doubt, switch it off and call. I keep them clear of banking details (a local charity provides a shopping service for them. when/if they can't get out to the local shops) and usually set up a new email address. Their online profile remains low and I get very few calls - but they're now able to email and have video calls with friends and distance family members, even get onto Facebook to join in with local groups (with a warning not to be tempted by any adverts that they'll see - again, if there's something they might like, call and let me, or one of my team of volunteers, take a look first).