I think a protection racket is usually a 'pay your dues or else something mysterious will happen to your shop', ie, the people demanding the money will wreak you up. Joining NATO seems, to me anyway, like joining a Body Corporate.... everyone pools their money and resources to help the areas that need attention.
With Russia right on Finland's doorstep, joining NATO seems like a good way to get Germany's brand spanking new expensive military and the USA/UK nukes to help Finland out if Russia steps over the line. I'm not sure I entirely see the downside for Finland...?
As a member state of the EU, Finland has access to Germany's military, because there is a directive that says that if any EU country is attacked, then all other states will defend it with all they have available. Nato is "double protection" only.
Ah, I see. I didn't realise the EU had that agreement.
So I guess the difference is that NATO offers the resources of the US, UK and Canada... and since the US currently (before Germany decided to start spending) spends more than the next 9 countries combined, it's not, ah, nothing. The UK is no slouch in the military spending department either. I honestly didn't realise that NATO had such significant military resources at its disposal.