I mean that the three story tellers downloaded infected software that locked the system but downloading Kaspersky unlocked it. One was LaTeX packages the other little nightmares 2 the game and my brother downloaded a design software.
The LaTeX package made the system unusable and encrypted data, asking for money for decryption. (windows7)
The game also made the system unresponsive and started uploading data, additionally social media accounts pf the owner were hacked. (Windows 10)
In both scenarios the owner didn't have Kaspersky and downloaded it only after infection, and it made the system function normally again. Although it didn't decrypt the files in the first case.
In the case of my brother his social media accounts were hacked and system started dying but he just relaunched Kaspersky (he paused it cuz crack asked him to do so lol) and the system survived functioning as always (although he had to rescue his accounts manually).

While it is debatable whether Kaspersky actually cleaned all the malware from the system, we can agree that the fact that system was rescued for the user to prepare for the re_installation is a good service.