if you need to process these in your intranet- get a server or PC with lots of memory. Command line tools such as
uniq -c are a good first start to do simple analyses, assuming that the data is reasonably clean.
Alternatively process datafiles in the cloud. New customers get a free tier there. Upload files to, say, Google BigQuery and process them with their other tools (e.g. Cloud Dataprep which would calculate summaries for each column, during upload).
However, you probably shouldn't do this with confidential user data where data protection laws apply.