Reallocated sectors are usually normal as a drive gets older. Manufacturers know parts of the drive which hold data will fail as it ages. So they add a few thousand spare sectors at the end of the drive. When a regular sector stops working, the drive updates its firmware to use a spare (reserve) sector in its place. From then on, every time the drive would read or write data to the bad sector, it uses the reserve sector instead. The reallocated sector count is just the number of sectors which have been mapped to reserve sectors. The reallocated event count is how many sectors the drive thinks may need mapping.
So it's normal for these counts to be high in an old drive. What you need to watch out for is if these counts suddenly increase by a lot. That's usually a sign the drive is dying. In that case, replacing the drive is your only option.
If you don't have much money and the OS is on a SSD, then a 5400 RPM hard drive should be fine. (Avoid the WD 5400 RPM drives - they have a head parking issue which can make games stutter. That pretty much limits you to Seagate or Toshiba. HGST drives are also good - even though they merged with WD, they're older Hitachi designs which don't have the head parking issue.)
Sequential speeds (speed at which large files are read/written) is more a function of how new the HDD is. The newer drives write data at a higher density. So a single rotation of the drive platter contains more data than a single rotation of an older drive. So a new 5400 RPM drive can be faster than an old 7200 RPM drive for large files.
4k speeds (speed at which small files are read/written) are more dependent on the RPM. The drive positions the heads in the proper track, then has to wait for the correct part of the platter to rotate under the heads. 7200 RPM drives rotate 33% faster than 5400 RPM drives, so their 4k speeds are 33% faster. But 7200 RPM drives still top out at about 1 MB/s (1.5 MB/s if you enable NCQ). A SSD can typically hit 30-70 MB/s 4k speeds, which is why it's so important to have your OS on a SSD.
Likewise, while the 7200 RPM drive will be faster for games than a 5400 RPM drive, it will only be 33% faster at most. If you're concerned about the speed of loading your games, you are far, far better off saving money by getting a 5400 RPM drive, and using the saved money to help buy a SSD in the future. Then put the games on the SSD.
If your current SSD has enough extra space and you use Steam for games, Steam allows you to put games on multiple drives. Just move the game you're currently playing to the SSD. When you finish or lose interest in the game, move it back to the HDD. Move your next game to the SSD.
https://forums.tomshardware.com/threads/steam-libraries-on-multiple-drives.2450763/
If you don't use Steam and install the games directly on the D: drive (HDD), but you have extra space on the C: drive (SSD), tell me. There's a trick you can do using something called directory junctions which can make Windows think a game is on your D: drive, even if you've temporarily moved it to the C: drive.
The bigger concern is that you are running without backups. You really should be making backups, at least of your most-essential data. If you need, you can use a flash drive to copy your most important data, then take your friend's laptop to a place with fast Internet and back up your data to the cloud. Or if your phone has some storage, you can copy to that, go someplace with fast WiFi, and re-upload it to the cloud like Google Drive or Microsoft OneDrive.