I use Revolut, mainly as a back-up solution and also for when travelling outside of the Eurozone. But I generally only keep €200 or so in it.
I think there are two ways that Revolut can be "less secure" (either in terms of fraudulent transactions or in terms of getting money back) than the "traditional banks".
Firstly, the Revolut card is a debit card (as I understand it). So if a scammer can use it to make a purchase, the money's gone immediately, and you have to fight to get it back.
Secondly, many/most people using Revolut put their card on Apple/Google pay. As I understand it, it just takes a single authorization in Revolut to put that card into any Apple/Google pay app. After that, the scammer can use the card as much as they want without any additional verification.
In contrast, with a traditional credit card, the money isn't gone immediately, Once you get the bill, you can dispute the transaction. And, if you stick with using the plastic card, it is easy to find out whether the transaction was via chip-and-pin, contactless, mag stripe or cardholder not present. If it was chip-and-pin, then extremely unlikely to be fraudulent. If anything else, you can dispute it and stand a very high chance of getting your money back.
Over the years, I've spotted 3 fraudulent charges made to my credit cards - BOI Mastercard and corporate AMEX. In all cases, a simple phone call was enough to get the charges cancelled.