Its bullshit to paint an invasion as aid. This is what imperialist do.
The soviets invaded afaganistan for the same reasons as the us did later and Briton did before.
To protect their borders from afar,
To create and protect trade deal favorable to their country,
To spread their ideology.
And by the way I read a book about the history of afaganistan called: Games Without Rules: The Often Interrupted History of Afghanistan.
It outlined how the three main invasion of Afghanistan all followed the same basic lines, motivations and results. They devastated Afghanistan and created a situation where they would be invaded again.