spammyTitle
If not, what can?
ISP's often will advertise "high speed internet" but they are actually using the term poorly.
Your connection to the internet is like water flowing down a stream or river. You can either have a small stream that moves water at 5mph, or a large river that moves water at 5mph. If you put a paper boat in the stream or big river, both will move at the same speed. If all you need to do is move a single paper boat, the stream is just fine. TF2 and most other games (when you are not downloading maps or mods or updates) requires very little bandwidth to run, and are like the paper boat, they will travel at the same speed in the stream or river. However if you want to move a large container ship or 100's of paper boats at the same time, you are going to need a river.
Basically if you have a stable and reliable connection, the ISP's "speed" such as 50Mbps download vs 5Mbps download will make zero difference in your ping. However, if you have multiple people streaming youtube or netflix at the same time, you will very quickly and easily use up that 5Mbps causing high ping. What can also cause high ping though is a shitty router in conjunction with multiple people using the internet at the same time for various tasks.
And then there is also the whole ISP routing to the server that can have a dramatic difference in your ping. They can take very efficient direct paths to the server, or they can bounce you all over the country or state prior to you reaching your destination.
If you run net_graph you can see the constant kb/s speed the game is using up and down. It's very low like maybe 30-50 Kb/s.