Personal computer to use for bitcoin client
A full copy of the blockchain is needed by "full node" clients such as Bitcoin Core, correct.  (The current size is now over 109 GiB.) But Bitcoin Core now supports pruning, where it downloads and validates the entire blockchain but discards most of it. In that case you can use it with less than 1 GB of disk space.

There are also many "thin" clients that do not need to download the entire blockchain at all.  See the wallet list on Bitcoin.org and look for those marked "simplified validation".  These clients need only a small amount of disk space.  This approach slightly reduces the security, as it is theoretically possible to trick such a client into accepting an invalid transaction, but for average users it is likely sufficient.

In short, there are plenty of ways for anyone to use Bitcoin on a personal computer without needing 100 GB of disk space.