Oracle started before microcomputers (PCs) were anything but toys. In 1983, they were multiplatform: mainframes and minicomputers. a 1983 minicomputer might have 2 CPUs, each good for 2 MIPS, 8 MB of RAM and primary storage of as much as a gigabyte or two of disks.
In the early 2000s, a serious database machine -- say, a Sun E10000 - had up to 64 CPUs, running at 400-500MHz each, 64 GB of RAM, and a huge cabinet full of disks.
Now you can call up a SuperMicro VAR and order a 64-core AMD EPYC server with 2TB of RAM and 4 TB of NVMe drives, that talks to other machines over a 100Gb/s ethernet, for a price around the same as a used Tesla S85.
If your database is under 2TB, it all fits in RAM on commodity hardware, where commodity is defined as "anyone with a credit card can order it without even talking to sales".
Could you explain ?
Personally I use Oracle (and hopefully one day PG) because it gives me guarantees on data integrity and these guarantees help me to think about my programs more easily.