In space, no one can hear you... smell.

Dr. Derek Zoolander

According to the oversight committee on cromulent projects (OCCP), the scheme as set forth would eventually acquire too much mass and collapse into itself as a black whole [sic]. However, setting Ludicrous as a revised upper size limit and establishing the diameter at 186,000 miles, thereby limiting a light speed…

All of the above and additionally no technology pissing contest called the Cold War.

You mean this idea?