I think the DUP overestimate their importance. 10 votes is of course still 10 votes, but as the Tories are so divided and many leaving/ losing the whip has slashed their slender DUP reliant majority in parliament. It's probably more critical now that any deal finds favour with a decent chunk of Labour MP's than the DUP in order to get it through.
And the SNP for one are lapping it up.