Without a welfare state, open borders is ideal. Incentives …

A society without a border isn't a nation, and will undoubtedly be preyed upon. It's a temporary state, until it's conquered either externally by military force, or internally by cultural infiltration.

Open borders is an oxymoron. A border is a boundary. Within this context, open means to lack a boundary. It's more accurate to say no border or borderless.

Once conquered a border will be established. A border is a tool used for protection and conservation of society and culture.

Secured borders are great for vetting individuals based on desirable qualities. Let the useful ones in that will be a societal net positive, and keep the riff raff out.

Open borders in the sense of, immigrants come in, follow a streamlinrd, easy process and begin working here. Not the buracracy and strife they go through today. This brings in beneficial, value adding people to the country.