Pushback on those intent on destabilizing Venezuela

There is a solution for Venezuela and all South American countries to push back against those intent on destabilizing the countries of the south. Brazil figured it out but did not take it far enough. Countries in South America should require all visitors to obtain a VISA and the cost of this should be a minimum of $500 US dollars or maybe $1000. This would not only raise considerable hard currency for the country but would reduce the number of unwelcomed vivitors to the respective country. It would also send a clear message to those that would undermine the sovreignty of the respective country. Personas non grata are not welcome.