What I mean is that it will be there but the user won't notice because he doesn't see a slowdown, etc. Techies can deal with that by monitoring, etc. How many people worldwide are techies?
Majority of malware will cause no slowdown (specially true for RATs and infostealers). Malware that causes slowdown, by the time user feels it, it would have already done its job.
Security setups, even when overcomplicated, fail too.
Good habits, such as avoiding torrents, cracks, keygens and other pirated content, not believing everything seen in emails as well as on ad banners, knowing that if something is too good to be true then it probably is, all that goes a long way and is less prone to failure (like everything else, not 100%).
For these habits, you don’t need to obtain masters in cybersecurity. Of course, it is naive to believe that everyone will have them, hence different security apps exist.
Even on business environments, employees are expected to be trained. When they are not, layered security setups fail and it is a recipe for disaster.
Highly technical and sophisticated attacks rarely happen, majority of times there will be some very obvious tell-tale signs.
For example, that email from GM will be coming from protonmail.com, not from the company domain.
Attackers pray for and prey upon the attacked user not to pay attention and to take shortcuts.
Remember that Linus Tech Tips account takeover, had he noticed that the “contract” pdf is 700MB (highly impossible for a legit pdf to be this size) he wouldn’t have been hacked. His security failed.
So it’s important for people to:
1.) pay their dues
2.) pay attention
3.) refuse to do what they are told in email and over the phone, rather log-in to their online account
The layered security setup is then optional but not unnecessary.
A lot of security apps blindly trust signed, reputable executables, so supply chain attacks will go right through in any case.
Supply chain attacks however are extremely rare, much more frequently, DJVU/Stop ransom and Agent Tesla are infecting systems because someone wanted a cracked game.
This is why, when investigating botnets, frequently it’s discovered that vast majority of the infrastructure is in third-world countries, where users are much more likely to rely on piracy.
On Android, majority of issues lie in apps that I got no clue why anyone over the age of 12 will want to install, table below provided by Bitdefender.
Even to properly layer your security, knowledge is still required. Nowadays there are loads of resources users can absorb, if they are lazy, it’s on them. That OEM McAfee won’t help them much.
TLDR: between a trained user that knows what they are doing and a user who installs an arsenal of security tools, the latter is more prone to getting an infection. One can always be both.