I assume you're living in a (relatively) rich Western/Eastern country?
While $10 might not be a lot in the US or Europe, for example, it is if you live in a country where 10 bucks is a week's wage...
And that for 30 cards that won't get you anywhere... (The water splinter doesn't even have magic in the starter deck...)
A couple of months ago, I conducted an experiment to see how far one could get without spending extra money: I only invested what I could earn on SteemIt and the apps. I had the advantage that I know my way around here, know where to go to earn a little extra, ánd had experience playing SM, which allowed me to progress faster. (This was before DEC came into play, though - but the beta cards were about 1/3 or even 1/4 the cost they are now). I got to level 3 summoners. The price to level up any further was simply too high... even with all the advantages I had...
I'm still all for a free-to-play version. I'm convinced it will attract more users. But during this last year, I learned the hard way that it is of no use to fight for that. It's only energy going to waste....