You should have rolling log files of limited size and limited quantity. The issue isn't that it's a text file, it's that they're not following pretty standard logging procedures to prevent this kind of thing and make logs more useful.
Essentially, when your log file reaches a configured size, it should create a new one and start writing into that, deleting the oldest if there are more log files than your configured limit.
This prevents runaway logging like this, and also lets you store more logging info than you can easily open and go through in one document. If you want to store 20 gb of logs, having all of that in one file will make it difficult to go through. 10 2 gb log files is much easier. That's not so much a consumer issue, but that's the jist of it.
The U.S. has a lot of fuckin things wrong with it but goddamn it's nice you can't be jailed for talking about how terrible it is