my guess would be there either scraped or port scanned proxies
for 25$ they wont be private or shared, not for 50k lols
anyways as for scraped proxies never more 3-5k live at any given time
i speak from 12 years scraping and port scanning proxies.
scraping proxies means scraping public proxies others have simply posted
they have a hi death rate, as anyone else with a scraper can scrape those same proxies.
port scanned proxies - is also public proxies, there not private no matter what anyone tells you
port scanned proxies can not be scraped or harvested, they have to be scanned from isp networks.
and i havnt come across anyone in 12 years getting 50k live port scanned public proxies.
most ive seen was 20k few years back.
also make sure u dont get conned. alot of people will do this, sell u a list like this , example
1 proxies posted multiple times on the same ip with a different port to make there lists bigger
when u see something like that, there reaching... just be careful and ask for a 50k test list
if u get 50k live proxies ill eat my hat
100.5.6.6:8080
100.5.6.6:80
100.5.6.6:3128
ps 1 possible way to get 50k proxies , a botnet and if anyone here offers to sell u into that run a mile
botnet = malware infested pc controlled by a host and there ips sent out. avoid.