So even with the hardware you'd need to download a DVD player for $15.00 from the Windows "store," unless you were upgrading directly from Win 7 Pro or Win 8.1 with Media Center. At least that was the state of play when I made my Win 10 installation DVD last summer, so none of the PCs I've installed Win 10 on have a native DVD player. It's possible that newer versions have one, but I haven't bothered to make a new installation DVD because I never use the Win 8/10 media player anyway. For the last couple of years I've used a VLC media player which is free and plays DVDs:
http://www.videolan.org/vlc/index.html
Here's an article about Win 10's screwy DVD player policy from last August 5:
http://betanews.com/2015/08/05/microsoft-releases-windows-dvd-player-for-windows-10-free-for-some-but-not-for-others/
Weird, but as I say not a deal breaker as there are better alternatives available for free, as is the case for most other stuff missing from Win 10. But you have to find it, install it, and then fiddle with it if Win 10 tries to break it as it often will.
That reminds me: if you go with a Win 7 system be sure to download and install an anti-virus as soon as you go online (Windows Defenders is fine, also free) because it's not built in and Win 7 catches bugs like a hungry anteater. Here's Windows Defender:
https://support.microsoft.com/en-us/help/14210/security-essentials-download
p.s. a system from Amazon may well have an anti-virus installed, but a fresh Win 7 installation won't.