I know the point that you are trying to make, but it's apples & oranges with DCL and Brewster. DCL was signed as one for the future/low risk gamble for £750k as a 19 yr old, with a view to being worked on by Unsworth & his coaches. Everton at the time were an established PL side with Lukaku, Kone & Valencia upfront. He did well in the u23's and was promoted, and has subsequently grown into a very good player, who is know worth £50m to £60m.
We were short of goals last season, the scorers of those goals were unlikely to replicate their feats for a number of reasons and we had £20m to £30m to spend on player/s to fill the goal scoring hole.
We chose to stick all our chips on an unproven 20 yr old to hit the ground running and score goals to keep us in the division. The idea that he was bought as 'one for the future', is revisionism by a number of our fan base. It was an extremely high risk strategy, and in hindsight should've been better handled with a season long loan with an option to purchase. When that wasn't available, we should've walked away. We've replicated Tammy A's PL season with swansea and paid top, top money for it, whilst they didn't. Brewster is now worth about £8m to £10m.