Clokwork
There's no need to be afraid of outdated systems (this doesn't mean you have to rush out and install Windows XP; everything is good in moderation 🙂). Some large state-owned enterprises still operate on legacy equipment (PCs, SCADA systems, machine tools, etc.).
You need a good antivirus (for example, ESET Internet Security, Kaspersky), a firewall and knowledge of the basics of security practices in any OS. Also, after EOL, do not use applications built into Windows 10, such as Edge or Mail; install third-party software for these tasks.
For the "full paranoia" level, I suggest installing Linux and keeping all sensitive information there, using Windows 10 only for gaming, watching videos, and reading forums, etc.
This is not 100% protection, as no system is 100% secure; risks always exist, they just need to be managed wisely. Especially in our case, when there may not be a real alternative in the Windows world for many more years.