>>63861772 (OP)>Developing countries like Brazil, South Korea and TurkeyAre these even considered developing countries. I have always thought of developing countries as places as Sudan, Kenya, or India; not SK, Brazil, OR Turkey, kek. All three of those are past 'developing' anyhow.
They have the advantages of cheaper labor (cheaper than most 'western' countries), larger pool of arms developers/ engineers (South Korea), and an actual incentive to build up (SK and Turkey both either have neighbors breathing down their neck, or want to expand outwards). These all either allow or require larger arms industries.
Selling weapons is highly lucrative, especially considering most countries are looking to replace cold-war era equipment. All three of ur countries provide cheap solutions for replacement, either through lucrative agreements, local production, or generally cheaper products. Not to mention many "1st world" countries have moved much more towards service economies since the 1991.