By default, proxychains uses the strict_chain option which means every proxyserver has to be live for it to work and even if one of the servers is down, then the proxychains fails. There is another option called dynamic_chain using which you can use proxychains even if some of the servers are not live. To make proxychains use dynamic_chain, open the proxychains.conf file
then in this file, comment the line strict_chain, and remove the comment from the line dynamic_chain.
Now proxychains will run even if some servers are down.