Many people believe that all of the content on internet is public domain.
What is public domain? The term "public domain" refers to creative materials that are not protected by intellectual property laws such as copyright, trademark, or patent laws. The public owns these works, not an individual author or artist. Anyone can use a public domain work without obtaining permission, but no one can ever own it.
Many people do not realise that just because anyone is free to look at or use content on internet it is not necesarily public domain. People believe that all the content of facebook and social media is public domain. That is not true. If you upload an image to facebook that you have taken on your camera then you own the copyright of the image. When you sign up to facebook you give your consent for facebook to use it on their platform. However you can still complain if someone downloads your content to their own website and claims it is their own. In the same way you can't record a song from the radio and then release it as your own work.
The gpx files on internet plaforms such as strava, wikiloc etc are protected by copyright. You can't download them and then upload them as you own. You can download the files to follow the walks or put a link to the url and invite another person to do the walk with you but you can't upload it to your profile and claim it to be your own.
Here are some extracts from the terms of service from some places which publish gpx files. They all recognise that the creator of a walk holds the copyright.
The User must be the owner of the intellectual property rights of the shared User Content whether by being the author, original owner or by holding the relevant rights.
You represent and warrant that: (i) you are authorized to create your account, whether individually or on behalf of an organization; (ii) you own the Content posted by you on or through the Services or otherwise have the right to grant the rights and licenses set forth in these Terms; (iii) the posting and use of your Content on or through the Services does not and will not violate, misappropriate or infringe on the rights of any third party, including, without limitation, privacy and data protection rights, publicity rights, copyrights, trademark and/or other intellectual property rights; and (iv) you agree to pay for all royalties, fees, and any other monies owed by reason of Content you post on or through the Services.
If you feel that any Materials or User Material are infringing your copyright rights, we encourage you to contact us immediately. Upon our receipt of a proper notice of claimed infringement under the DMCA, we will respond expeditiously to remove, or disable access to, the material claimed to be infringing and will follow the procedures specified in the DMCA to resolve the claim between the notifying party and the alleged infringer who provided the content in issue. Our designated agent (i.e., the proper party) to whom you should address such notice is listed below.
I suppose it depends on howmuch effort you spent making the files. If you spent a long time cleaning your files to make them perfect, adding waypoints etc then it might be very annoying if someone else steals all your files and uploads them to their own profile. To be honest if your files are important to you then you shouldn't share your files. Nobody will be sympathetic because most people believe that everything on internet is public domain.