i recently re-installed ES File Explorer and was floored with how much work went into it! i've used it years ago so i could see the difference. it is now also a

i recently re-installed ES File Explorer and was floored with how much work went into it! i've used it years ago so i could see the difference. it is now also an app manager, ftp client, bluetooth/network explorer.. and it's FREE! i'm also not seeing any ads. how can they afford to put so much work into this app?